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Abstract Background Readmissions in psychiatric inpatient care may reflect problems in the provision of care, but the underlying factors are not well known. We examined the associations of patient characteristics (sociodemographic factors, diagnoses), treatment (duration, previous episodes, neuromodulation) and ward overload with psychiatric inpatient readmissions and multiple readmissions in Finland. Methods We used a routinely collected data pool from one hospital district and followed all 2052 hospitalizations that started in 2018. The outcomes were readmission within 30 days and one year, and among those with readmission, the number of readmissions. Results Of the patients, 11% had readmission within 30 days and 33% had readmission within one year. Women, those with previous hospitalizations, those with an ICD-10 diagnosis from the ‘behavioural syndromes associated with physiological disturbances and physical factors / disorders of adult personality and behaviour’ group, those with a diagnosis from the ‘neurotic, stress-related and somatoform disorders’ group, those with psychotic disorders, and those who received neuromodulation treatment were more likely to have readmissions. Having a diagnosis of ‘disorders of psychological development’ or ‘behavioural and emotional disorders with onset usually occurring in childhood and adolescence’ was associated with a lower likelihood of readmission. The duration of treatment and ward overload during the index period were not associated with readmission. Conclusions The findings of this study suggest possible risk factors for readmission and can be used to plan psychiatric care. To some degree, the risk factors varied between different readmission types. It is important to examine whether there are unmet treatment needs in psychiatric inpatient care for children and adolescents.

OBJECTIVE: Leisure-time physical activity (PA) has been hypothesized to reduce the likelihood of occupational injuries, but it is unclear whether this association varies between workplace and commuting injuries. The aim of this study was to examine the association between PA and risk of workplace and commuting injuries. METHODS: Data were derived from the Finnish Public Sector study including 82 716 person-observations (48 116 participants). PA was requested repeatedly in four questionnaire surveys between 2000–2012. The average level of PA from two subsequent questionnaires was used to assess long-term PA. To obtain a 1-year incidence of injuries, participants were linked to occupational injury records from the national register. Logistic regression analysis with generalized estimating equations was used to examine the association between PA and injury risk. The analysis was adjusted for age, sex, education, work schedule, job demand, sleep difficulties, cardiovascular diseases, diabetes, and depression for workplace and commuting injuries, and workplace injuries were additionally adjusted for physical heaviness of an occupation and injury risk by occupation. RESULTS: Higher level of PA was associated with a lower risk of workplace injuries compared to inactive participants [odds ratio (OR) 0.85, 95% confidence interval (CI) 0.73–0.98]. This association was most marked in the ≥50-year-old age group (OR 0.78, 95% CI 0.64–0.99). No association between the PA and the risk for commuting injuries was observed. CONCLUSION: Higher PA is associated with lower risk of workplace injuries particularly among older employees.

OBJECTIVE: This paper discusses the past and present highlights of working hours and health research and identifies key research needs for the future. METHOD: We analyzed over 220 original articles and reviews on working hours and health in the Scandinavian Journal of Work, Environment & Health published during the last 50 years. Key publications from other journals were also included. RESULTS: The majority of identified articles focussed on the effects of shift and night work, with fewer studying long and reduced working hours and work time control. We observed a transition from small-scale experimental and intensive field studies to large-scale epidemiological studies utilizing precise exposure assessment, reflecting the recent emergence of register-based datasets and the development of analytic methods and alternative study designs for randomized controlled designs. The cumulative findings provide convincing evidence that shift work and long working hours, which are often associated with night work and insufficient recovery, increase the risk of poor sleep and fatigue, sickness absence, occupational injuries, and several chronic health conditions such as cardiovascular diseases and cancer. The observed risks are strongly modified by individual and work-related factors. CONCLUSIONS: Although the observed health risks of shift work and long working hours are mostly low or moderate, the widespread prevalence of exposure and the hazardousness of the many associated potential outcomes makes such working time arrangements major occupational health risks. Further research is needed to identify exposure–response associations, especially in relation to the chronic health effects, and to elucidate underlying pathways and effective personalized intervention strategies.

OBJECTIVES: This study aimed to estimate the validity of self-reported information on ever-night shift work among women with and without breast cancer and illustrate the consequences for breast cancer risk estimates. METHODS: During 2015–2016, 225 women diagnosed with breast cancer and 1800 matched controls without breast cancer employed within the Danish hospital regions during 2007–2016 participated in a questionnaire-based survey. Their reported night shift work status was linked with objective payroll register day-by-day working hour data from the Danish Working Hour Database and the Danish Cancer Registry. For the breast cancer patients and their matched controls, we estimated sensitivity and specificity for ever-working night shifts using the payroll data as the gold standard. We also used quantitative bias analysis to estimate the impact on relative risk estimates for a hypothetical population. RESULTS: For breast cancer patients, we observed a sensitivity of ever-night shifts of 86.2% and a specificity of never-night shifts of 82.6%. For controls, the sensitivity was 80.6% and the specificity 83.7%. Odds ratio for breast cancer in a hypothetical population decreased from 1.12 [95% confidence interval (CI) 1.03–1.21] to 1.05 (95% CI 0.95–1.16) when corrected by the sensitivity and specificity estimates. CONCLUSION: This study shows that female breast cancer patients had slightly better recall of previous night shift work than controls. Additionally, both breast cancer patients and controls recalled previous never-night shift work with low specificity. The net effect of this misclassification is a small over-estimation of the relative breast cancer risk due to night shift work.

OBJECTIVE: This study aimed to compare the utility of risk estimation derived from questionnaires and administrative records in predicting long-term sickness absence among shift workers.METHODS: This prospective cohort study comprised 3197 shift-working hospital employees (mean age 44.5 years, 88.0% women) who responded to a brief 8-item questionnaire on work disability risk factors and were linked to 28 variables on their working hour and workplace characteristics obtained from administrative registries at study baseline. The primary outcome was the first sickness absence lasting ≥90 days during a 4-year follow-up.RESULTS: The C-index of 0.73 [95% confidence interval (CI) 0.70–0.77] for a questionnaire-only based prediction model, 0.71 (95% CI 0.67–0.75) for an administrative records-only model, and 0.79 (95% CI 0.76–0.82) for a model combining variables from both data sources indicated good discriminatory ability. For a 5%-estimated risk as a threshold for positive test results, the detection rates were 76%, 74%, and 75% and the false positive rates were 40%, 45% and 34% for the three models. For a 20%-risk threshold, the corresponding detection rates were 14%, 8%, and 27% and the false positive rates were 2%, 2%, and 4%. To detect one true positive case with these models, the number of false positive cases accompanied varied between 7 and 10 using the 5%-estimated risk, and between 2 and 3 using the 20%-estimated risk cut-off. The pattern of results was similar using 30-day sickness absence as the outcome.CONCLUSIONS: The best predictive performance was reached with a model including both questionnaire responses and administrative records. Prediction was almost as accurate with models using only variables from one of these data sources. Further research is needed to examine the generalizability of these findings.

OBJECTIVES: This study aimed to evaluate effects of night and shift work patterns on type 2 diabetes (T2D) and hypertension in a longitudinal study, with detailed information on working hours. METHODS: The cohort comprised about 28 000 nurses and nursing assistants employed for more than one year 2008–2016 in Stockholm, Sweden. The employee register held detailed individual information on daily working hours. Information on diagnoses came from national and regional registers. Hazard ratios (HR) and confidence intervals (CI) were estimated by discrete-time proportional hazard models, adjusting for sex, age, country of birth, and profession. RESULTS: During follow-up in 2013–2017, we identified 232 cases of T2D and 875 of hypertension. We observed an increased risk of T2D, but not hypertension, among employees who worked only night shifts the previous year (HR 1.59, 95% CI 1.02–2.43) and those with intensive shift work (>120 afternoon and/or night shifts the previous year: HR 1.67, 95% CI 1.11–2.48) compared to only day work. There was a non-significantly increased risk of T2D related to mixed day and afternoon shifts (HR 1.34, 95% CI 0.97–1.88). We observed tendencies in increased risk of T2D related to frequent spells of ≥3 consecutive night shifts and with number of years with exclusive (but not mixed) night work. CONCLUSIONS: Permanent night work and frequent afternoon and/or night shifts were associated with an increased risk of T2D the following year, but not hypertension. The T2D risk was, to some extent, affected by frequent spells of several night shifts in a row and by cumulative years with permanent night work.

OBJECTIVE: This study aimed to find out whether utilizing a shift schedule evaluation tool with ergonomics recommendations for working hours has favorable effects on the incidence of occupational injuries. METHODS: This 4-year prospective cohort study (2015–2018) consisted of a dynamic cohort of healthcare shift workers (N=29 237) from ten hospital districts and six cities in Finland. Working hour characteristics and occupational injuries were measured with daily registry data. Multilevel generalized linear model was used for the analyses, and the estimates were controlled for hierarchical structure of the data and confounders. RESULTS: Ward heads of the cities used the shift schedule evaluation tool 3.2 times more often than ward heads of the hospital districts. Overall incidence of workplace and commuting injuries did not differ between users and non-users of the evaluation tool. The incidence of dislocations, sprains, and strains was lower in the users than non-users [adjusted odds ratio (OR) 0.88, 95% confidence interval (CI) 0.78–0.99]. Approximately 13% of this association was mediated by increase in realized shift wishes and 10% by increase in single days off. In subgroup analyses, the incidence of workplace injury (OR 0.83, 95% CI 0.69–0.99), and among types of injuries, the incidence of dislocations, sprains, and strains (OR 0.69, 95% CI 0.55–0.85) and falling, slipping, tripping, or overturning (OR 0.75, 95% CI 0.58–0.99) were lower in users than non-users among employees of the cities, but no association was found among employees of the hospital districts. CONCLUSION: The use of ergonomics recommendations for working hours is associated with a reduced risk of occupational injuries.

Objectives To investigate the concurrent changes in part-time work and sickness absence (SA) in healthcare. Another aim was to investigate the role of age and sex on different concurrent trajectory groups.Design Prospective cohort study.Setting Public hospital districts (n=10) and cities (n=11) in Finland.Participants Payroll-based objective working hour data of the healthcare sector in Finland for 28 969 employees in 2008–2019 were used. The final sample included those working shifts with 3 consecutive years of data and without baseline (≥14 days) SA.Primary outcomes Part-time work (yes or no) and months of SA.Measures Group-based trajectory modelling to identify concurrent changes in part-time work, and months of SA while controlling the time-variant amount of night work and multinomial regression models for relative risk (RR) with 95% CIs were used.Results Four-group trajectory model was the best solution: group 1 (61.2%) with full-time work and no SA, group 2 (16.9%) with slowly increasing probability of part-time work and low but mildly increasing SA, group 3 (17.6%) with increasing part-time work and no SA, and group 4 (4.3%) with fluctuating, increasing part-time work and highest and increasing levels of SA. Men had a lower (RR 0.49–0.75) and older age groups had a higher likelihood (RRs 1.32–3.79) of belonging to trajectory groups 2–4.Conclusions Most of the sample were in the trajectory group with full-time work and no SA. The probability of part-time work increased over time, linked with concurrent low increase or no SA. A minor group of employees had both an increased probability of part-time work and SA. Part-time work and other solutions might merit attention to promote sustainable working life among healthcare employees.

Abstract Background In health care, the shift work is arranged as irregular work shifts to provide operational hours for 24/7 care. We aimed to investigate working hour trends and turnover in health care via identification of time-related sequences of work shifts and absences among health care employees. The transitions between the work shifts (i.e., morning, day, evening, and night shifts), and absences (days off and other leaves) over time were analyzed and the predictors of change in irregular shift work were quantified. Methods A longitudinal cohort study was conducted using employer-owned payroll-based register data of objective and day-to-day working hours and absences of one hospital district in Finland from 2014 to 2019 (n = 4931 employees). The working hour data included start and end of work shifts, any kind of absence from work (days off, sickness absence, parental leave), and employee’s age, and sex. Daily work shifts and absences in 2014 and 2019 were used in sequence analysis. Generalized linear model was used to estimate how each identified sequence cluster was associated with sex and age. Results We identified four sequence clusters: “Morning” (60% in 2014 and 56% in 2019), “Varying shift types” (22% both in 2014 and 2019), “Employee turnover” (13% in 2014 and 3% in 2019), and “Unstable employment (5% in 2014 and 19% in 2019). The analysis of transitions from one cluster to another between 2014 and 2019 indicated that most employees stayed in the same clusters, and most often in the “Varying shift types” (60%) and “Morning” (72%) clusters. The majority of those who moved, moved to the cluster “Morning” in 2019 from “Employee turnover” (43%), “Unstable employment” (46%) or “Varying shift types” (21%). Women were more often than men in the clusters “Employee turnover” and “Unstable employment”, whereas older employees were more often in “Morning” and less often in the other cluster groups. Conclusion Four clusters with different combinations of work shifts and absences were identified. The transition rates between work shifts and absences with five years in between indicated that most employees stayed in the same clusters. The likelihood of a working hour pattern characterized by “Morning” seems to increase with age.

OBJECTIVE: This study aimed to examine the effects of various aspects of night and shift work on the risk of incident ischemic heart disease (IHD) and atrial fibrillation (AF) using detailed and registry-based exposure data. METHODS: This prospective cohort study included >30 300 healthcare employees (eg, nurses, nursing assistants) employed for at least one year in Region Stockholm 2008–2016. Information on daily working hours was obtained from a computerized administrative employee register and outcomes from national and regional registers. Using discrete-time proportional hazard models, we analyzed the outcomes as functions of working hour characteristics the preceding year, adjusted for sex, age, country of birth, education, and profession. RESULTS: We observed 223 cases of IHD and 281 cases of AF during follow-up 2009–2016. The risk of IHD was increased among employees who the preceding year had permanent night shifts compared to those with permanent day work [hazard ratio (HR) 1.61, 95% confidence interval (CI) 1.06–2.43] and among employees working night shifts >120 times per year compared to those who never worked night (HR 1.53, 95% CI 1.05–2.21). When restricted to non-night workers, the risk of IHD was increased for employees having frequent quick returns from afternoon shifts. No increased risks were observed for AF. CONCLUSIONS: Night work, especially working permanent night shifts and frequent night shifts, is associated with an increased risk of incident IHD but not AF. Moreover, frequent quick returns from afternoon shifts (among non-night workers) increased IHD risk. Organizing work schedules to minimize these exposures may reduce IHD risk.

Abstract Background Hospital physicians’ work includes on-call duties to provide 24/7 health care. Previous studies using self-reported survey data have associated long working hours and on-call work with sleep difficulties. To reduce recall bias, we complemented survey data with payroll-based objective data to study whether hospital physicians’ realized working hours are associated with sleep. Methods The study was nested within the Finnish Public Sector study. We used survey data on 728 hospital physicians (mean age 43.4 years, 62% females) from 2015 linked to realized daily working hour data from 3 months preceding the survey. The associations of working hour characteristics with sleep quantity and quality were studied with multinomial logistic regression analysis adjusted for demographics, overall stressfulness of life situation, control over scheduling of shifts, and hospital district. Results One fourth (26%) of the participants reported short (≤6.5 h) average sleep duration. Frequent night work (> 6 shifts/91 days) was associated with short sleep (OR 1.87 95%CI 1.23–2.83) compared to no night work. Approximately one third (32%) of the physicians reported insufficient sleep. Physicians with long weekly working hours (> 48 hours) had higher odds for insufficient sleep (OR 1.78 95%CI 1.15–2.76) than physicians with short weekly working hours ( 12 shifts/3 months OR 2.00 95%CI 1.08–3.72), frequent night work (OR 1.60 95%CI 1.09–2.37), and frequent short shift intervals (≤11 hours; > 12 times/3 months OR 1.65 95%CI 1.01–2.69) compared to not having these working hour characteristics. Nearly half of the physicians (48%) reported at least one sleep difficulty at least two times a week and frequent night work increased odds for difficulties in initiating sleep (OR 2.43 95%CI 1.04–5.69). Otherwise sleep difficulties were not associated with the studied working hour characteristics. Conclusion We used realized working hour data to strengthen the evidence on on-call work and sleep quality and our results advice to limit the frequency of night work, on-call shifts, short shift intervals and long weekly working hours to promote hospital physicians’ sufficient sleep.

Administrative data accumulating daily from hospitals would provide new possibilities to assess work shifts and patient care. We aimed to investigate associations of work unit level average work shift length and length of patient in-hospital stay, and to examine the role of nurse-patient-ratio, year, night work, age, work units and working hours at the work units for these estimations. The data for this study were based on combined administrative day-to-day patient and pay-roll based objective working hour data of employees of one hospital district in Finland for 2013-2019. Three patient measures were calculated: the overall length of in-hospital stay, the length of in-hospital stay before a medical procedure and the length of in-hospital stay after a medical procedure. A Generalized Linear Mixed Model (GLMM) with multivariate normal random effects was used with Penalized Quasi-Likelihood for relative risk ratios (RR) with 95% confidence intervals (CI). The results showed that compared to 10 hours work shifts were associated with a decreased likelihood of the overall length of in-hospital stay (RR 0.94, 95% CI 0.94, 0.95) and length of in-hospital stay after a medical procedure among all occupations (RR 0.94, 95% CI 0.92, 0.97). These associations retained the magnitude and direction in the models additionally adjusted for work, employee, and patient characteristics, and the associations were weaker for nurses than among all occupations. To conclude, compared with the standard work shifts, 8-10 hours work shifts seem to be associated with longer, and >10 hours work shifts with shorter length of in-hospital stay. Administrative data provides feasible possibilities to investigate working hours and length of in-hospital stay.

The impact of continuing job education and professional development on early exit from the labor market is unclear. This systematic review examined how continuing job education or professional development influences the retention of current employment. We searched the PubMed and Embase databases from their start dates to January 2023. Two reviewers screened the full texts of relevant reports and assessed the methodological quality of the included studies using the adapted Effective Public Health Practice Project quality assessment. We qualitatively synthesized the results of the included studies. We screened 7338 publications and included 27 studies consisting of four cohort and 23 cross-sectional studies in the review. The participants of the selected studies were mostly from the health sector (24 studies). There were 19 studies on staying or leaving a current job, six on employee turnover intention, two on job change, one on return to work, one on early retirement, and one on employment. Continuing employee development or training opportunities were associated with increased intention to stay in a current job, decreased intention to leave a current job, decreased employee turnover intention, job change, or early retirement and with faster return to work. One of the two studies that examined the role of age showed that continuing employee development is a more important factor for retaining current employment among younger than older employees. A few studies found that job satisfaction and commitment fully mediated the relationship between employee development and employee intention to leave current employment. This study suggests that participating in professional training/development is related to a lower risk of leaving current employment.

OBJECTIVE: This study aimed to investigate the effects of various aspects of night and shift work regarding incident cerebrovascular disease (CeVD). METHODS: The cohort included 26 667 women and 3793 men (nurses and nursing assistants) who were employed for at least one year 2008–2016 in Region Stockholm, Sweden. Information about the cohort and working hours were obtained from a computerized employee-register and diagnoses were retrieved from national and regional registers. We used discrete time proportional hazard models to assess the risk of CeVD (2009–2017), in relation to work hour characteristics, adjusting for sex, age, country of birth, education and profession. RESULTS: We observed an excess risk of CeVD (N=223) among employees who, during the preceding year, worked night shifts >30 times [hazard ratio (HR) 1.44, 95% confidence interval (CI) 1.04–1.99] or ≥3 consecutive night shifts >15 times (HR 1.69, 95% CI 1.18–2.42) or with >30 quick returns (5 years) of exposure to night shift work (HR 1.87, 95% CI 1.27–2.77), all supported by a dose–response pattern. CONCLUSIONS: Our results show that the risk of CeVD among nurses and nursing assistants is associated with night shift work. The number of years with night shift work, the frequency of night shifts per year, the frequency of consecutive night shifts, and short recovery after night shifts influenced the risk. Work schedules aiming at minimizing these aspects of night shift work may reduce the risk.

Abstract Background There is inconsistent evidence that long working hours and night work are risk factors for sickness absence, but few studies have considered variation in the length of exposure time window as a potential source of mixed findings. We examined whether the association of long working hours and night work with sickness absence is dependent on the length of exposure to the working hour characteristics. Methods We analysed records of working hours, night work and sickness absence for a cohort of 9226 employees in one hospital district in Finland between 2008 and 2019. The exposure time windows ranged from 10 to 180 days, and we used Cox’s proportional hazards models with time-dependent exposures to analyse the associations between working-hour characteristics and subsequent sickness absence. Results Longer working hours for a period of 10 to 30 days was not associated with the risk of sickness absence whereas longer working hours for a period of 40 to 180 days was associated with a lower risk of sickness absence. Irrespective of exposure time window, night work was not associated with sickness absence. Conclusions It is important to consider the length of exposure time window when examining associations between long working hours and sickness absence, whereas the association between night work and sickness absence is not similarly sensitive to exposure times.

BackgroundThe association between health and working hours is hypothesized to be reciprocal, but few longitudinal studies have examined changes in both health and working hour patterns over time. We examined combined trajectories of self-related health and two working hour patterns (working

OBJECTIVES: Data mining can complement traditional hypothesis-based approaches in characterizing unhealthy work exposures. We used it to derive a hypothesis-free characterization of working hour patterns in shift work and their associations with sickness absence (SA). METHODS: In this prospective cohort study, complete payroll-based work hours and SA dates were extracted from a shift-scheduling register from 2008 to 2019 on 6029 employees from a hospital district in Southwestern Finland. We applied permutation distribution clustering to time series of successive shift lengths, between-shift rest periods, and shift starting times to identify clusters of similar working hour patterns over time. We examined associations of clusters spanning on average 23 months with SA during the following 23 months. RESULTS: We identified eight distinct working hour patterns in shift work: (i) regular morning (M)/evening (E) work, weekends off; (ii) irregular M work; (iii) irregular M/E/night (N) work; (iv) regular M work, weekends off; (v) irregular, interrupted M/E/N work; (vi) variable M work, weekends off; (vii) quickly rotating M/E work, non-standard weeks; and (viii) slowly rotating M/E work, non-standard weeks. The associations of these eight working-hour clusters with risk of future SA varied. The cluster of irregular, interrupted M/E/N work was the strongest predictor of increased SA (days per year) with an incidence rate ratio of 1.77 (95% confidence interval 1.74–1.80) compared to regular M/E work, weekends off. CONCLUSIONS: This data-mining suggests that hypothesis-free approaches can contribute to scientific understanding of healthy working hour characteristics and complement traditional hypothesis-driven approaches.

OBJECTIVE: This study aimed to determine the associations of working hour characteristics with short (1–3 days) sickness absence (SA) among retail workers. METHODS: As part of “RetailHours-project”, 4046 employees of 338 Finnish retail stores were included. Registry-based data on working hour characteristics and short SA were utilized. A case-crossover design was used and the odds ratios (OR) were controlled for the clustering effect and working hour characteristics. RESULTS: There were strong dose–response relationships between percent of short (25% of work times. Weekly working hours >40 hours were associated with SA among part-time workers [odds ratio (OR) 2.22, CI 1.65–2.98], women (OR 1.62, CI 1.27–2.07) and among workers

Abstract The human DNA methylome is responsive to our environment, but its dynamics remain underexplored. We investigated the temporal changes to DNA methylation (DNAme) in relation to recovery from a shift work disorder (SWD) by performing a paired epigenome-wide analysis in an occupational cohort of 32 shift workers (25 men, age = 43.8 ± 8.8 years, 21 SWD cases). We found that the effect of vacation on DNAme was more prominent in the SWD-group as compared to controls, with respect to the amount of significantly differentially methylated positions (DMPs; P unadj

OBJECTIVES: We investigated the association of working hours with occupational injuries in hospital shift work. METHODS: Registry data of occupational injuries of hospital employees from 11 towns and 6 hospital districts were linked to daily payroll data to obtain working hours for 37 days preceding the first incidence of the injury (N=18 700). A case-crossover design and associated matched-pair interval analysis were used to compare working hour characteristics for three separate hazard windows among the same subjects. Conditional logistic regression was used to calculate odds ratios (OR) with 95% confidence intervals (CI). RESULTS: We found an elevated risk of an occupational injury for workdays with evening shifts (OR 1.09, 95% CI 1.03–1.14) and workdays following night shifts (OR 1.33, 95% CI 1.17–1.52). After excluding commuting injuries, the risk increased during the evening shifts (OR 1.15, 95% CI 1.09–1.23) and the work days following night shifts (OR 1.44, 95% CI 1.24–1.69), but was no more significant during the morning shifts. Injury risk increased following a week of ≥5 morning shifts or ≥3 evening shifts, but did not increase according to the number of preceding night shifts or quick returns. The length of the work shift (OR 1.22, CI 1.06–1.42) – not the length of the weekly working hours – was associated with an increased risk. CONCLUSIONS: The results indicate an increased occupational injury risk during the evening shifts and during work days following night shifts, with the risk increasing according to the number of evening but not night shifts.

OBJECTIVES: This discussion paper aims to provide scientifically based recommendations on night shift schedules, including consecutive shifts, shift intervals and duration of shifts, which may reduce health and safety risks. Short-term physiological effects in terms of circadian disruption, inadequate sleep duration and quality, and fatigue were considered as possible links between night shift work and selected health and safety risks, namely, cancer, cardio-metabolic disease, injuries, and pregnancy-related outcomes. METHOD: In early 2020, 15 experienced shift work researchers participated in a workshop where they identified relevant scientific literature within their main research area. RESULTS: Knowledge gaps and possible recommendations were discussed based on the current evidence. The consensus was that schedules which reduce circadian disruption may reduce cancer risk, particularly for breast cancer, and schedules that optimize sleep and reduce fatigue may reduce the occurrence of injuries. This is generally achieved with fewer consecutive night shifts, sufficient shift intervals, and shorter night shift duration. CONCLUSIONS: Based on the limited, existing literature, we recommend that in order to reduce the risk of injuries and possibly breast cancer, night shift schedules have: (i) ≤3 consecutive night shifts; (ii) shift intervals of ≥11 hours; and (iii) ≤9 hours shift duration. In special cases – eg, oil rigs and other isolated workplaces with better possibilities to adapt to daytime sleep – additional or other recommendations may apply. Finally, to reduce risk of miscarriage, pregnant women should not work more than one night shift in a week.

OBJECTIVES: In a prospective study among workers in an airline company, we explored whether change in work stress symptoms or night shifts was associated with nutrient intake. METHODS: Participants in a workplace type 2 diabetes (T2D) prevention study completed a questionnaire on lifestyle, work stress symptoms, work schedule, and food intake at baseline and after 2.4-years follow-up (211 men and 155 women, 93% with increased risk for T2D). Multiple linear regression models with covariates were used to explore the associations between change in work stress symptoms or night shifts and change in nutrient intake during the follow-up. RESULTS: Among men, an increase in stress and a decrease in perceived workability was associated with a higher proportion of energy (E%) from fat [β 0.6, 95% confidence interval (CI) 0.07–1.11, β 1.3, 95% CI 0.57–2.05] and saturated fat (β 0.3, 95% CI 0.02–0.58, β 0.5, 95% CI 0.14–0.90), respectively. Furthermore, a decrease in workability was associated with lower vitamin C intake (β-9.2, 95% CI -16.56– -1.84) and an increase in sleepiness with higher E% from saturated fat (β 0.7, 95% CI 0.00–0.15). Among women, an increase in work-related fatigue was associated with higher alcohol intake (β 7.5, 95% CI 1.25–13.74) and an increase of night shifts was associated with higher E% from fat (β 0.24, 95% CI 0.00–0.47) and saturated fat (β 0.17, 95% CI 0.04–0.29). CONCLUSIONS: Work stress symptoms were associated with a reduction in diet quality especially among men. The possible impact of work stress symptoms on workers’ dietary habits should be acknowledged and the assessment of dietary habits should consequently be incorporated into occupational health examinations.

OBJECTIVES: Shift work is a risk factor for chronic diseases, and physical inactivity can have an influence on this association. We examined whether intra-individual changes in working time characteristics were associated with changes in physical inactivity and examined the risk factors for physical inactivity among shift workers in a 17-year longitudinal study cohort. METHODS: Study participants were 95 177 employees from the Finnish public sector. Work schedule information was based on questionnaire responses and additional register-based working time characteristics for 26 042 employees. The associations between working time characteristics and physical inactivity were examined using a fixed-effects logistic model. To investigate the risk factors for physical inactivity among shift workers, the odds ratios (OR) of worktime control and having small children were calculated. RESULTS: Compared with day work, shift work without night shifts was associated with physical inactivity among men [OR 1.38, 95% confidence interval (CI) 1.09–1.74], whereas shift work with night shifts was negatively associated with physical inactivity among women (OR 0.85, 95% CI 0.76–0.96). Register-based working time data confirmed that workers with a higher percentage of night shifts had a lower risk of physical inactivity. Having small children was associated with physical inactivity among shift workers (OR 1.47, 95% CI 1.32–1.65). CONCLUSIONS: Both survey and objective working hour data revealed that workers having work schedules with night shifts were more likely to be physically active. Having small children was a risk factor for physical inactivity among shift workers.

The headline in a main Finnish newspaper on 16 November announced: “Trust and interest for published science has increased in Finland”. I would have hypothesized that evidence-based knowledge was losing the game against the rush of non-scientific and commercial information – but I was wrong. A 3-year follow-up survey among the Finland population was clear on this. Could the growth in electronic and social media information actually be causing people to search for knowledge based on scientific facts? Forty-five years have passed since the publication of the first issue of the Scandinavian Journal of Work, ­Environment & Health (SJWEH) in January 1975. The Journal is unique due to its non-profit profile in a sea of large, commercial publishing house journals. With a current impact factor of 3.491, SJWEH is recognized for its high quality and interesting content. The main aim of the Journal has always been to promote good and impactful research in the field of occupational and environmental health and safety. The Journal makes a difference by providing its readership with innovative topics, systematic reviews on existing knowledge, and papers using advanced research methods. Over the years, the scientific focus areas of occupational research, research methods, and academic publishing have undergone major changes. In fact, the Journal’s transformation over more than four decades can be used as a good example of how occupational research and publishing policy has adapted to the new trends in scientific knowledge and information technology. Well-known professor of epidemiology and specialist in occupational medicine, Sven Hernberg was the first Editor-in-Chief (EC) of the Journal. SJWEH was based on earlier ancestor journals (1), but in practice Sven had to start from scratch both scientifically and economically. Together with Sven, Markku Nurminen, epidemiologist and biostatistician, and native English-speaking copy editor Georgianna Oja belonged to the first editing team. SJWEH was launched as the joint activity of the Swedish, Danish, Norwegian and Finnish national research institutes. Even though the Journal’s main focus in the beginning was on occupational medicine, toxicology and epidemiology, Sven wanted to support some developing fields of research at the time such as research of musculoskeletal disorders and biological monitoring. He was interested in preventive actions and the initialization of long follow-up studies in occupational medicine (2). The very first SJWEH paper was a review on neurophysiological methods (3). The first paper on psychosocial factors, published by Theorell in 1977, was on the association of psychosocial factors in concrete work with myocardial infarction (4). Based on the 20 “citation classics” (defined as publications with ≥100 citations) of the five most distinguished occupational medicine journals (5), citation classics dealing with toxicology were published in each decade during those times. However, well-cited papers on solvents appeared only during the 1970s and 1980s and were instrumental in the phasing out of organic solvents-based paints. Citations classics on work-related musculoskeletal disorders emerged in the 1980s and gained in popularity in the later decades (5). Compared to other occupational health journals, SJWEH had the second highest number of citation classics during the early decades of its existence. With >900 citations in Scopus, a 1993 paper on the association of psychosocial factors with musculoskeletal diseases by Bongers (6) was among one of the most cited. I took up the position of Assistant EC after Markku in 1994. During the next few years, Sven and I updated our editing processes. A new electronic publishing system was created in 1998, making it possible to shift to a joint co-editor model. Several new Associate Editors (AE) were brought on board, increasing the expertise of the Journal significantly and making the editing process more interactive. Eira Viikari-Juntura, Petter Kristensen, Per Malmberg, Thomas Schneider, Lars Hagmar, Michiel Kompier, Kjell Larson, and Gunnar Aronson joined the Journal in the first wave starting 1999–2000. When Sven retired at the end of 1999, I became the EC sharing, however, the key management and decision-making together with Eira, who took on the role of Assistant EC in 2000. As a supplement to the paper version, an electronic version of the Journal was launched in 2001. In his last editorial before retiring (7), Sven emphasized the significance of the need to shift the focus to new areas of research. While traditional occupational diseases were – and still are – a burden in many countries, he highlighted that the main roadblock in their remedy is not additional research but implementation of already existing knowledge (7). Taking the lead, we started to focus on new areas where existing knowledge was not great, especially psychosocial issues and musculoskeletal disorders, while maintaining a strong presence in epidemiological and clinical research on occupational epidemiology. During the 1990s, we had already started to publish editorials and reviews in all issues of the Journal. Several of the latter became citation classics, for example those on exposure assessment and musculoskeletal issues by Burdorf (8) and Burdorf & Sorock (9) and a review on shift work and cardiovascular diseases by Bøggild & Knutsson (10). We also published consensus reports on key issues like the new Helsinki criteria for diagnosis and attribution on asbestos, asbestosis and cancer (11), extensively cited later, up to its update a few years ago (12), and special issues on growing research areas like work-related stress: health-risks, mechanisms and countermeasures (13) and shift work and health (14). These special issues included several reviews that also became citation classics. The review on psychosocial factors and mental health by Stansfeld & Candy (15), in particular, has been cited >900 times based on Scopus, as well as a review on work stress and coronary heart disease by Kivimäki and colleagues (16) (>500 times). During the 2000s, in addition to relevance, emphasis was placed on shortening article processing time and improving accessibility of the Journal (17). Some new AE were brought onto the team to improve the Journal’s expertise in new key research areas. Being among the key scientists publishing and actively reviewing for the Journal, Alex Burdorf, Bengt Järvholm, Göran Kecklund, Jos Verbeek, Hannu Norppa, Antero Aitio, and Jens Peter Bonde all started as new AE. To speed up the flow of manuscripts and improve accessibility, we shifted to a full electronic submission and review process and launched the ”online first” policy, making all papers open access until their publication in the print version. These efforts, along with higher quality submissions increased citations and raised the impact factor. When Georgianna retired in 2009, Lisa O’Donoqhue-Lindy started as the new Managing Editor. In addition to being responsible for copy editing, Lisa promoted the electronic and open access services of the Journal and has always been very active in its development and benchmarking against other journals. From 2008 to today, the impact factor of the Journal has doubled, and currently we hold a close second among all journals in the field of occupational and environmental health. During the same period, the number of submitted papers has doubled allowing us to be more selective and publish only the best research, which is depicted in the current acceptance rate of 15%. Since the beginning of 2012, the non-profit Nordic Association of Occupational Safety and Health (NOROSH) has published the Journal. As earlier, the Nordic research institutes play a key role as founding members of NOROSH. Papers published on epidemiology, especially those associated with psychosocial factors (18–21), long working hours and shift work (22–26), as well as papers on musculoskeletal disorders, physical activity, work careers and return-to-work (27–31) performed better than average with respect to citations. However, papers introducing or using new methodologies (32–34) have gained much attention, too. The last two years have been historical for the Journal for several reasons. Sven sadly passed away (2). When Eira retired as Assistant EC in 2018, Alex Burdorf, Head of the Department of Public Health at Erasmus University Medical Centre joined me as co-EC. And when I decided to step down at end of 2019, Reiner Rugulies, Professor of Psychosocial Issues and Mental Health at the Danish National Research Centre for the Working Environment became EC alongside Lex, after earlier having been an AE. I will continue as an AE for the topics of shift work and working hours. In the meantime, several new AE have joined the team: Karin Broberg, Håkan Wallin, David Lombardi, Karl-Christian Nordby, Carel Hulshof, Susanne Svendsen, Hermann Burr and Vivi Schlünssen several years ago, and, more recently, Annina Ropponen, Henrik Kolstad, Cécile Boot, and Paul Kuijer. In the future, as the editorial team has pointed out, the Journal will place greater emphasis on scientific quality and innovative research topics and methods (35). Staying ahead of the Open Science Movement, we recently decided to take the important step towards becoming a fully fledged open access journal. Starting in 2020, open access will be by opt-out only and in 2022, we will publish 100% unlocked content. Thus the Scandinavian Journal of Work, Environment & Health will remain a relevant, high-quality, non-profit scientific journal that is unique in many ways. References 1. Smith DR. A history of the Scandinavian Journal of Work, Environment & Health. Scand J Work Environ Health. 2016;42(3):177-80. https://www.sjweh.fi/show_abstract.php?abstract_id=3558 2. Rantanen J. Professor Sven Hernberg, 1934-. Scand J Work Environ Health. ;45(3):527-8. https://doi.org/10.5271/sjweh.3849 3. Seppalainen AM. Applications of neurophysiological methods in occupational medicine. A review. Scand J Work Environ Health. 1975;1(1):1-14. https://doi.org/10.5271/sjweh.2865 4. Theorell T, Olsson A, Engholm G. Concrete work and myocardial infarction. Scand J Work Environ Health. 1977;3(3):144-53. https://doi.org/10.5271/sjweh.2779 5. Gehanno JF, Takahashi K, Darmoni S, Weber J. Citation classics in occupational medicine journals. Scand J Work Environ Health. 2007;33(4):245-51. https://doi.org/10.5271/sjweh.1139 6. Bongers PM, de Winter CR, Kompier MA, Hildebrandt VH. Psychosocial factors at work and musculoskeletal disease. Scand J Work Environ Health. 1993;19(5):297-312. https://doi.org/10.5271/sjweh.1470 7. Hernberg S. Towards a new millennium. Scand J Work Environ Health. 1999;25(6):465-9. https://doi.org/10.5271/sjweh.468 8. Burdorf A. Exposure assessment of risk factors for disorders of the back in occupational epidemiology. Scand J Work Environ Health. 1992;18(1):1-9. https://doi.org/10.5271/sjweh.1615 9. Burdorf A, Sorock G. Positive and negative evidence of risk factors for back disorders. Scand J Work Environ Health. 1997;23(4):243-56. https://doi.org/10.5271/sjweh.217 10. Boggild H, Knutsson A. Shift work, risk factors and cardiovascular disease. Scand J Work Environ Health. 1999;25(2):85-99. https://doi.org/10.5271/sjweh.410 11. Tossavainen K. Asbestos, asbestosis, and cancer: the Helsinki criteria for diagnosis and attribution. Scand J Work Environ Health. 1997;23(4):311-6. https://doi.org/10.5271/sjweh.226 12. Wolff H, Vehmas T, Oksa P, Rantanen J, Vainio H. Asbestos, asbestosis, and cancer, the Helsinki criteria for diagnosis and attribution 2014: recommendations. Scand J Work Environ Health. 2015;41(1):5-15. https://doi.org/10.5271/sjweh.3462 13. Härmä M, Kompier MA, Vahtera J. Work-related stress and health--risks, mechanisms and countermeasures. Scand J Work Environ Health. 2006;32(6):413-9. https://doi.org/10.5271/sjweh.1047 14. Härmä M, Kecklund G. Shift work and health - how to proceed? Scand J Work Environ Health. 2010;36(2):81-4. https://doi.org/10.5271/sjweh.2902 15. Stansfeld S, Candy B. Psychosocial work environment and mental health--a meta-analytic review. Scand J Work Environ Health. 2006;32(6):443-62. https://doi.org/10.5271/sjweh.1050 16. Kivimaki M, Virtanen M, Elovainio M, Kouvonen A, Vaananen A, Vahtera J. Work stress in the etiology of coronary heart disease--a meta-analysis. Scand J Work Environ Health. 2006;32(6):431-42. https://doi.org/10.5271/sjweh.1049 17. Härmä M, Viikari-Juntura E. Härmä M, Viikari-Juntura E. Development of the Scandinavian Journal of Work, Environment & Health-the challenge of relevance, speed and accessibility. Scand J Work Environ Health. 2007;33(1):1-3. https://www.sjweh.fi/show_abstract.php?abstract_id=1058 18. Gilbert-Ouimet M, Trudel X, Brisson C, Milot A, Vezina M. Adverse effects of psychosocial work factors on blood pressure: systematic review of studies on demand-control-support and effort-reward imbalance models. Scand J Work Environ Health. 2014;40(2):109-32. https://doi.org/10.5271/sjweh.3390 19. Nielsen MB, Indregard AM, Overland S. Workplace bullying and sickness absence: a systematic review and meta-analysis of the research literature. Scand J Work Environ Health. 2016;42(5):359-70. https://doi.org/10.5271/sjweh.3579 20. Rugulies R, Aust B, Madsen IE. Effort-reward imbalance at work and risk of depressive disorders. A systematic review and meta-analysis of prospective cohort studies. Scand J Work Environ Health. 2017;43(4):294-306. https://doi.org/10.5271/sjweh.3632 21. Klingelschmidt J, Milner A, Khireddine-Medouni I, Witt K, Alexopoulos EC, Toivanen S, et al. Suicide among agricultural, forestry, and fishery workers: a systematic literature review and meta-analysis. Scand J Work Environ Health. 2018;44(1):3-15. https://doi.org/10.5271/sjweh.3682 22. Oakman J, Neupane S, Proper KI, Kinsman N, Nygard CH. Workplace interventions to improve work ability: A systematic review and meta-analysis of their effectiveness. Scand J Work Environ Health. 2018;44(2):134-46. https://doi.org/10.5271/sjweh.3685 23. Bannai A, Tamakoshi A. The association between long working hours and health: a systematic review of epidemiological evidence. Scand J Work Environ Health. 2014;40(1):5-18. https://doi.org/10.5271/sjweh.3388 24. Jorgensen JT, Karlsen S, Stayner L, Andersen J, Andersen ZJ. Shift work and overall and cause-specific mortality in the Danish nurse cohort. Scand J Work Environ Health. 2017;43(2):117-26. https://doi.org/10.5271/sjweh.3612 25. Vistisen HT, Garde AH, Frydenberg M, Christiansen P, Hansen AM, Andersen J, et al. Short-term effects of night shift work on breast cancer risk: a cohort study of payroll data. Scand J Work Environ Health. 2017;43(1):59-67. https://doi.org/10.5271/sjweh.3603 26. Torquati L, Mielke GI, Brown WJ, Kolbe-Alexander T. Shift work and the risk of cardiovascular disease. A systematic review and meta-analysis including dose-response relationship. Scand J Work Environ Health. 2017. https://doi.org/10.5271/sjweh.3700 27. Virtanen M, Jokela M, Madsen IE, Magnusson Hanson LL, Lallukka T, Nyberg ST, et al. Long working hours and depressive symptoms: systematic review and meta-analysis of published studies and unpublished individual participant data. Scand J Work Environ Health. 2018;44(3):239-50. https://doi.org/10.5271/sjweh.3712 28. Arends I, van der Klink JJ, van Rhenen W, de Boer MR, Bultmann U. Predictors of recurrent sickness absence among workers having returned to work after sickness absence due to common mental disorders. Scand J Work Environ Health. 2014;40(2):195-202. https://doi.org/10.5271/sjweh.3384 29. Jakobsen MD, Sundstrup E, Brandt M, Jay K, Aagaard P, Andersen LL. Effect of workplace- versus home-based physical exercise on musculoskeletal pain among healthcare workers: a cluster randomized controlled trial. Scand J Work Environ Health. 2015;41(2):153-63. https://doi.org/10.5271/sjweh.3479 30. Commissaris DA, Huysmans MA, Mathiassen SE, Srinivasan D, Koppes L, Hendriksen IJ. Interventions to reduce sedentary behavior and increase physical activity during productive work: a systematic review. Scand J Work Environ Health. 2016;42(3):181-91. https://doi.org/10.5271/sjweh.3544 31. Reeuwijk KG, van Klaveren D, van Rijn RM, Burdorf A, Robroek SJ. The influence of poor health on competing exit routes from paid employment among older workers in 11 European countries. Scand J Work Environ Health. 2017;43(1):24-33. https://doi.org/10.5271/sjweh.3601 32. van der Beek AJ, Dennerlein JT, Huysmans MA, Mathiassen SE, Burdorf A, van Mechelen W, et al. A research framework for the development and implementation of interventions preventing work-related musculoskeletal disorders. Scand J Work Environ Health. 2017;43(6):526-39. https://doi.org/10.5271/sjweh.3671 33. Schelvis RM, Oude Hengel KM, Burdorf A, Blatter BM, Strijk JE, van der Beek AJ. Evaluation of occupational health interventions using a randomized controlled trial: challenges and alternative research designs. Scand J Work Environ Health. 2015;41(5):491-503. https://doi.org/10.5271/sjweh.3505 34. Thiart H, Lehr D, Ebert DD, Berking M, Riper H. Log in and breathe out: internet-based recovery training for sleepless employees with work-related strain - results of a randomized controlled trial. Scand J Work Environ Health. 2015;41(2):164-74. https://doi.org/10.5271/sjweh.3478 35. McInnes JA, Akram M, MacFarlane EM, Keegel T, Sim MR, Smith P. Association between high ambient temperature and acute work-related injury: a case-crossover analysis using workers’ compensation claims data. Scand J Work Environ Health. 2017;43(1):86-94. https://doi.org/10.5271/sjweh.3602 36. Burdorf A, Härmä M. The future of Scandinavian Journal of Work, Environment & Health in the era of open science. Scand J Work Environ Health ;45(3):(213-4. https://doi.org/10.5271/sjweh.3826

OBJECTIVE: This study examined the associations between shift work and use of antihypertensive, lipid-lowering, and antidiabetic medications. METHODS: Survey data from two cohorts of Finnish men (N=11 998) and women (N=49 944) working in multiple occupations where shift work was used were linked to national Drug Prescription Register data, with up to 11 years of follow-up. In each cohort, age-stratified Cox proportional hazard regression models were computed to examine any incident use of prescription medication for each of the three medical conditions, separately comparing each of two groups of rotating shift workers (those whose schedules included night shifts, and those whose schedules did not include night shifts) with day workers who worked in a similar range of occupations. RESULTS: In the larger cohort, among participants aged 40–49 at baseline, shift work without night shifts was associated with increased use of type-2 diabetes medication after adjustments for sex, occupational status, marital status, alcohol consumption, smoking, and physical activity [hazard ratio (HR) 1.28, 95% confidence interval (CI) 1.01–1.62], while shift work with night shifts was associated with increased use of dyslipidemia medication after adjustments (HR 1.33, 95% CI 1.12–1.57). There were no such associations among younger and older shift workers. Also in the larger cohort, among those aged

ObjectivesStudies concerning the risk of metabolic syndrome associated with night work have shown inconsistent findings, due to imprecise working time data and cross-sectional design. We used register-based daily working time data to examine the risk of incident metabolic syndrome associated with night shift work.MethodsWorking time data collected between 2010 and 2018 of 5775 Taiwanese hospital workers were used to identify night shift workers and to calculate the number of night shifts. Metabolic syndrome was identified by annual occupational health examination results, which were linked to the working time data. Logistic regression models and generalized estimating equations were used to examine the association between night shift work and metabolic syndrome and the 5 components of metabolic syndrome.ResultsNight shift work is associated with a higher risk of developing metabolic syndrome (adjusted OR = 1.36, 95% CI = 1.04 to 1.78) and high waist circumference (adjusted OR = 1.27, 95% CI = 1.07 to 1.78) compared to day work. Among night shift workers, increased number of night shifts was associated with high blood pressure (adjusted OR = 1.15, 95% CI = 1.01 to 1.31).ConclusionsNight shift work is associated with metabolic risk factors. Long-term effects of circadian rhythm disruption on metabolic disturbances needs to be further studied.

Objectives To determine whether nurses working consecutive night shifts, or short transitions between shifts (quick returns (QRs)), yielded higher risk for pain complaints when compared with regular morning shifts. Sleep duration was tested as a potential mediator.Design Observational diary study.Setting Random hospitals.Participants Nurses with three-shift rotation (morning, evening and night), n=679, 22–63 years old.Outcomes measures Daily ratings of working hours, sleep and subjective pain complaints in six anatomical regions (head, neck/shoulder/upper back, upper extremity, low back, lower extremity and abdomen) for 28 days. In addition, we assessed demographics, habitual sleep and pain complaints, work and lifestyle factors. It was tested (1) whether the risk for pain complaints was higher after workday 3 versus after workday 2, and whether the difference was larger for consecutive night shifts versus consecutive morning shifts, and (2) whether the risk for pain complaints was higher after QRs versus after two morning shifts. Risk for pain complaints refers to combined increased risk for any pain and risk for increased intensity.Results Adjusted analyses showed no shift type by workday interaction for pain complaints in the neck/shoulder/upper back, upper extremities, low back, lower extremities or abdomen. For headache, a strong trend indicated that the risk was higher on workday 3 compared with workday 2 for night shifts (OR 1.13, 95% CI 0.99 to 1.28). The risk was lowered if sleep duration was taken into account (OR 0.37, 95% CI 0.17 to 0.81). No conclusive support was found for the risk for pain complaints being higher after QRs, compared with after morning shifts.Conclusions For five of six pain complaints, the hypotheses were not supported by the current data. For headache, we found potential support for a sleep-relieving effect on headache after working several nights in a row. Pain complaints were not instigated or exacerbated by an evening-to-morning transition between shifts.

OBJECTIVES: The aim of this study was to examine whether changes in work shifts and shift intensity are related to changes in difficulties to fall asleep, fatigue, and sleep length. METHODS: Questionnaire responses of hospital employees (N=7727, 93% women) in 2008, 2012, 2014 and 2015 were linked to daily-based records of working hours during three months preceding each survey. We used conditional logistic regression and longitudinal fixed-effects analyses to investigate odds ratios (OR) and 95% confidence intervals (CI) for each 25% within-individual change in the proportion of working hour characteristics in relation to changes in fatigue, difficulties to fall asleep, and 24-hour sleep length. RESULTS: Change in night but not in morning or evening shifts was associated with parallel changes in odds for longer sleep length (OR 1.45, 95% CI 1.28–1.64) and fatigue during free days (OR 1.38, 95% CI 1.16–1.64). Similarly, short shift intervals and having >2 but not >4 consecutive night shifts were associated with increased odds of fatigue during work and difficulties to fall asleep (OR 1.42, 95% CI 1.19–1.72 and OR 1.10, 95% CI 1.05–1.19, respectively). Among workers aged ≥50 years, the associations were the strongest between night shifts and longer sleep (OR 2.24, 95% CI 1.52–3.81) and between higher proportion of short shift intervals and fatigue during free days (OR 1.68, 95% CI 1.10–2.54). CONCLUSIONS: Among shift workers with fatigue or sleep problems, decreasing the proportion of night shifts and quick returns and giving preference to quickly forward-rotating shift systems may reduce fatigue.

The association of shift work with cardiovascular disease (CVD) has been studied for decades with new systematic reviews repeatedly being published (1–4). Based on 34 studies and over 2 million employees, the systematic review of Vyas et al (4) concluded a few years ago that shift work was associated with incident myocardial infarction, with a risk ratio of 1.23 [95% confidence interval (CI) 1.15–1.31]. In this issue, a new systematic review and meta-analysis on shift work and the risk of CVD is published. Based on 21 studies, including 10 new ones since the publication of Vyas et al (4), Torquati and colleagues (3) found that shift work was associated with coronary heart disease (CHD) morbidity with a pooled risk ratio of 1.26 (95% CI 1.10–1.43) and about 20% increased risk of death from CHD or CVD. The study also reports that risk of CVD events increased by 7.1% for every five years of exposure. Even though the classical study of Knutsson et al (5) showed that CVD increases with exposure up to 20 years, the exposure–response estimate based on the meta-analysis is novel. With the increasing number of original studies and systematic reviews over the years, our knowledge on the association between shift work and CVD should be growing. However, new studies often have old quality problems. Without improvement in quality, new studies may not sufficiently add to the knowledge base. Information and selection bias, insufficient or incorrect control of confounding, and imprecise exposure information have often been common challenges in studies of shift work and CVD (1, 2). Thus, we ask whether the quality of new studies reviewed by Torquati et al (3) has improved? And if not, how should future shift work and CVD studies be designed to overcome methodological challenges? Selection bias Earlier studies on shift work and CVD have discussed the possible role of selection, primarily as a source of negative bias, indicating that many may underestimate the true risk. A “healthy shift worker effect” may rise if mainly healthy employees are selected into shift work, for instance based on pre-employment screening or selection out of shift work due to insomnia or other health problems. Both options are possible since health check-ups and regulations for transfer to day work in cases of recognized health problems are included in current legislation in many countries. Since the association between shift work and chronic diseases like CVD and breast cancer attenuates after cessation of exposure (6, 7), restricting study populations to elderly cohorts of former shift workers – who have not been exposed for years – may overlook real associations. The recent Million Women Study (8), which found no association between shift work and cancer, included subjects of very advanced age. Starting follow-up at an older age may have resulted in the inclusion of more participants less susceptible to the effects of night shift work (7, 9). Furthermore, old age is associated with the accumulation of competing risk factors, diminishing the relative role of shift work compared to the other factors (10). In the current review, different risks of bias were systematically examined across all individual studies by a validated tool (11). Attrition was not possible to assess in 13 of the 21 published studies, and 1 had clearly a high attrition. If attrition was linked to the full cessation of exposure follow-up in some of the studies, we may have a negative bias of unknown magnitude in some of the published studies. Exposure assessment Already 20 years ago, Bøggild & Knutsson (1) suggested in their review of shift work and CVD that “different shift schedules should be distinguished to identify which type of shift schedule confers the smallest risk”. Torquati et al (3) studied the quality of exposure assessment of the individual studies by analyzing whether information on duration of exposure as well as shift intensity was available, as requested for instance by the International Agency for Research on Cancer (IARC) working group report on shift work and cancer studies (12). Torquati et al (3) also investigated the possible use of objective exposure information (payroll or other employer registers or diary data of working hours) of the published studies. Of 21 studies, 8 had additional information on the different elements of shift work exposure and only 4 could provide objective data on shift work exposure. The lack of life-time information on shift work could bias the evaluation of shift work health effects since this may mean that risks of long-term or early shift work exposure is overlooked. In addition, it is common that many day workers are exposed to shift work in the beginning of their career (13); thus, lack of information of earlier exposure attenuates the observed risk estimates. The use of objective registry-based shift work and health data has several benefits: it provides precise information on exposure less affected by information bias as well as outcome data less affected by attrition since data can be retrieved for all employees (14). However, the main limitations relate to the possibility of accessing company records on longer periods of exposure in addition to obtaining information on exposure outside the main occupation. Confounding and effect mediators Based on Torquati et al (3), all the 21 analyzed studies adjusted for age, body mass index, ethnicity, and socioeconomic status. However, besides increased energy intake (15) and weight gain (16), shift work disturbs sleep and may increase smoking (4). Adjustment for smoking may thus hide a true effect of shift work on smoking-related diseases. A recent study indicated that shift workers had similar leisure-time physical activity patterns as day workers but were more sedentary at work (17). As the authors note, in order to disentangle effect mediation from true confounding, we would need information on these factors not only during the pre-employment period but also repeatedly during and after exposure to shift work. In their sensitivity analysis, Torquati et al (3) investigated how various sources of potential bias influenced the observed overall risks. Studies were classified as having low, intermediate, or high risk of bias from either unreliable exposure assessment, insufficient adjustment for confounders, analytical methods, blinding of assessors, attrition, selective reporting, or funding. Rather surprisingly, the overall degree of bias had no strong influence on the magnitude of the reported risks, indicating that methodological shortcomings of the studied bias types may not explain the positive overall findings. However, this may not be the case for the reported positive dose–response relationship with duration of shift work. Of the five studies included in the analysis, three showed increasing risk with duration of shift work (18–20), while two showed no such trend (21, 22). The first three studies all relied on self-reported exposure and outcome information that was not blinded to exposure status, while the latter two relied on register information on exposure as well as outcome. For the other eight risk of bias parameters, all five studies were assessed as being equal. This actually questions the reliability of the reported 7.1% increasing relative risk per five years of shift work, which may be affected by recall bias and stresses the need for analyses based on objective exposure as well as objective outcome data (23, 24). In conclusion, the present review of Torquati et al (3) shows that even if the number of new publications on shift work and cardiovascular health increases, many of the new studies still include the well-known old sources of bias. Some light is seen in the acknowledgement of the need for better exposure assessment of shift work. The new case–control studies of shift work and breast cancer used interviews to get more precise and relevant information on exposure to night and shift work (7). However, the use of electronic records of working hours would be most optimal. For the cohort studies, we would need to combine the precise information on exposure to shift work with longer and more systematic follow-up. With objective information on shift characteristics, which are robust to differential recall, it may be possible to provide acceptable safety limits for the number of annual or consecutive night shifts for different exposure times and/or risk groups. Therefore, future etiological studies and research into the prevention of CVD risks in shift work needs to be based on the principle of obtaining precise and repeated information on exposure to shift work combined with long registry follow-up and repeated information on confounders and possible mediators.

Shift workers are at increased risk of health problems. Effective preventive measures are needed to reduce the unfavourable effects of shift work. In this study we explored whether use of digital participatory working time scheduling software improves employee well-being and perceived workability by analysing an observational cohort study as a pseudo-experiment. Participants of the Finnish Public Sector cohort study with payroll records available between 2015 and 2019 were included (N = 2427). After estimating the propensity score of using the participatory working time scheduling software on the baseline characteristics using multilevel mixed-effects logistic regression and assigning inverse probability of treatment weights for each participant, we used generalised linear model to estimate the effect of using the participatory working time scheduling software on employees’ control over scheduling of shifts, perceived workability, self-rated health, work-life conflict, psychological distress and short sleep (≤6 h). During a 2-year follow-up, using the participatory working time scheduling software reduced the risk of employees’ low control over scheduling of shifts (risk ratio [RR] 0.34; 95% CI 0.25–0.46), short sleep (RR 0.70; 95% CI 0.52–0.95) and poor workability (RR 0.74; 95% CI 0.55–0.99). The use of the software was not associated with changes in psychological distress, self-rated health and work-life conflict. In this observational study, we analysed as a pseudo-experiment, the use of participatory working time scheduling software was associated with increased employees’ perceived control over scheduling of shifts and improved sleep and self-rated workability.

Abstract Background Previous studies indicate that psychological, social, and organizational factors at work contribute to health, motivation, absence from work, and functional ability. The objective of the study was to assess the current state of knowledge of the contribution of psychological, social, and organizational factors to disability retirement by a systematic review and meta-analyses. Methods Data sources: A systematic literature search for studies of retirement due to disability in Medline, Embase, and PsychINFO was performed. Reference lists of relevant articles were hand-searched for additional studies. Data extraction: Internal validity was assessed independently by two referees with a detailed checklist for sources of bias. Conclusions were drawn based on studies with acceptable quality. Data synthesis: We calculated combined effect estimates by means of averaged associations (Risk ratios) across samples, weighting observed associations by the study’s sample size. Thirty-nine studies of accepted quality were found, 37 of which from the Nordic countries. Results There was moderate evidence for the role of low control (supported by weighted average RR = 1.40; 95% CI = 1.21-1.61) and moderate evidence for the combination of high demands and low control (although weighted average was RR = 1.45; 95% CI = 0.96-2.19) as predictors of disability retirement. There were no major systematic differences in findings between the highest rated and the lowest rated studies that passed the criterion for adequate quality. There was limited evidence for downsizing, organizational change, lack of employee development and supplementary training, repetitive work tasks, effort-reward imbalance to increase risk of disability pension. Very limited evidence was found for job demands, evening or night work, and low social support from ones superior. Conclusions Psychological and organizational factors at work contribute to disability retirement with the most robust evidence for the role of work control. We recommend the measurement of specific exposure factors in future studies.

Forty years has passed since the first issue of the Scandinavian Journal of Work, Environment & Health. Over these four decades of rapid change in scientific publishing, the Journal has stabilized its position as the top international periodical in Occupational and Environmental Health. Our latest (2014) impact factor is 3.454, with a 5-year impact factor of 4.060. The journal now ranks 21st of 160 journals in the Public, Environmental and Occupational Health category of the Journal Citation Report – and the best among more than a dozen occupational health journals on the list. Authors refer to articles that are important for their own new research. But what makes an important publication in occupational health research? At the very least, it should be an innovative and high-quality publication. One paper alone is rarely responsible for societal impact, but a good one can further catalyze, support, or enhance our understanding of the elements of good practical solutions and cost-effective interventions. The aim of Scand J Work Environ Health has always been to promote good and impactful research in the field of occupational and environmental health and safety and increase knowledge through scientific publication. Over the years, although the goals of the Journal have remained unchanged, scientific focus, research methods, and academic publishing itself have undergone a monumental change. Looking back, the first paper published in the Journal in 1975 was a review by Anna Maria Seppäläinen (1) on the applications of neurophysiological methods in occupational medicine. At that time, neurophysiological methods were recommended for the research and diagnosis of vibration and exposure to, for example, insecticides, carbon monoxide, acrylamide, and lead. The first issues of the Journal were rich in exposure assessment methodology and toxicology. Likewise, there were many papers related to occupational medicine. In the third issue from the same year, however, a paper did emerge on sleep length and adaption to shift work among Swedish railroad workers (2), varying the content. A study of the distribution of the research topics of 85 “citations classics” (ie, papers with >100 citations) from 1950 to 1997 in five major occupational medicine journals (including Scand J Work Environ Health) revealed some interesting findings. While a few citations classics dealing with toxicology were published during each decade, classics concerning solvents appeared only during the 1970s and 1980s, and those dealing with work-related musculoskeletal disorders emerged in the 1980s and increased significantly in the decades thereafter (3). During the last ten years, the most popular topics in the Journal have been occupational epidemiology, musculoskeletal disorders, and psychosocial factors. These papers also performed better than average with respect to citations (especially psychosocial factors), while papers on, eg, toxicology and respiratory disorders have appeared less frequently and have also been less frequently cited (4). During the last two years (see the “top-cited articles” www.sjweh.fi/list_top_cited.php) , many well-cited papers have investigated key issues relating to present working life, factors predicting return-to-work (5, 6), decreased sickness absence (7, 8), longer work careers (9, 10), and higher productivity (7, 11) at work. The solutions studied were often practical interventions related to work modifications and working hours, but also changes in individual, social or lifestyle factors. The evolution of the Journal’s contents seems to reflect the current trends in general occupational safety and health (OSH) research policies (see eg, http://www.perosh.eu/research-priorities/). The Journal has come a long way in updating its expertise and focus areas but is still open to all relevant topics in the area of occupational and environmental health. Also toxicology, which the Journal initially targeted, is still an issue in today’s working life. Especially primary preventive interventions, such as the lowering of the permissible exposure limits, are important even if their cost-effectiveness can be shown only years later. In general, we believe the Journal’s future research topics must address questions that can contribute to the resolution of challenges facing today’s and tomorrow’s working life. To obtain new knowledge about effective treatments for diseases or prevention strategies, experimental epidemiological methods have been the traditional choice, and the randomized controlled trial (RCT) has been considered as the gold standard. The occupational health problems of today have multiple etiologies, and – to overcome these problems – complex interventions are often needed. Moreover, it is often not sufficient to target these interventions solely at the individual but rather also at the working environment. As has been described in the paper by Schelvis et al (12) in this issue of the Journal, the RCT or a cluster RCT may be a challenging design to adopt in current working life. Other experimental and observational epidemiological designs exist, some of which have been used in areas other than occupational health. These designs offer more flexibility and feasibility for the intervention and are not as sensitive to the loss of subjects in the groups that are followed. Some of the observational methods can effectively utilize routinely collected data, resulting in lower costs and reduced risks of attrition in the studied samples. Many of these designs require sophisticated statistical skills in the analysis of the data, putting demands on the continuing education of researchers in the field. As the authors recommend, researchers carrying out systematic reviews should broaden their inclusion criteria to include these alternative designs, and guidelines should be developed to improve the reporting of studies utilizing such approaches. The use of new designs offers a new platform to examine the effectiveness of workplace and societal interventions. To invite submissions to this area, the Journal will introduce a new section “Experimental and quasi-experimental studies (quasi-experiments)”, where reviewers will be invited to comment. If the scientific content of journals and research methods employed have changed, then the academic publishing landscape itself has been turned on its head. Such upheaval have been driven by technology but also by the increasing number of scholarly and scientific players around the world and concerns relating to the commercial influence on scientific knowledge. According to a 2015 report (13), globally there are up to an estimated 10 000 journal publishers, approximately 5000 of which are included in Scopus. Only 650 English-language publishers – mostly from trade and professional associations – produced 11 550 journals or close to half of the total journal output by title. By the end of 2014, an incredible 28 100 scholarly peer-reviewed journals were in circulation, growing at a rate of 3.5% per year and publishing about 2.5 million articles annually. The US continues to dominate with 23% of output, but China is not far behind (17%) followed by the UK (7%), Germany (6%), Japan (6%), and France (4%). The biggest area of change stems from the rapid growth of open access (OA) journals. Although they are difficult to define due to the multiple models employed (eg, “gold”, versus “hybrid”, versus green”), at the time of writing, the Directory of Open Access Journals listed 10 477 “gold” or 100% OA titles, from 134 countries, totaling close to 2 million articles (https://doaj.org/). Scand J Work Environ Health continues to be a “hybrid” journal, which means the Journal has “locked” and “unlocked” content. Authors or their supporting network can purchase OA for EUR1300 per article or some articles are awarded OA status based on merit (eg, Editor’s Pick, highly cited paper). In 2014, majority of all Scand J Work Environ Health content (including editorials, articles, letters, commentary etc) was OA. The Journal would be eager to “flip” to gold status but unfortunately institutions have been slow to take up NOROSH membership, which comprises OA publishing of all accepted papers from authors affiliated with the organization, and income from the author processing charge (APC) is not enough to cover the Journal’s costs. We are not alone in facing this challenge. Without sufficient scale and a low-cost approach, most smaller journals would have to charge APC of anywhere from $2500 to $10 000 to cover their costs (13). The challenge going forward is to lower costs and increase output without cutting corners or reducing quality. For a commercially independent journal like Scand J Work Environ Health, there is literally no room to maneuver on revenue. For this reason, we continue to focus on maintaining high quality standards, a responsive and meaningful editorial process, and rapid online publication of articles to attract the best content and the strongest reviewers in the OSH field. The real dilemma ahead is the trend of funders to insist that authors not only publish OA articles but that they publish them in “gold” journals and, one step further, that authors aim for “green” publishing where feasible. The “green” model is one where, at first sight, it appears like “nobody pays”. The author takes the accepted and post-peer-reviewed paper and self-archives it in a repository. According to the Directory of OA repositories, the number has grown from 128 in 2005 to 2900 in 2015 (13). And while the objective behind “green” publishing is commendable, there is always a price to pay at the end of the day, mostly it will be smaller quality journals like Scand J Work Environ Health who will lose subscribers and APC fees. Even the big commercial publishing houses are wary of the “green” trend but at least they have the financial clout, negotiating authority, and economies of scale to manage the pending crisis. For the time being, Scand J Work Environ Health continues to be flexible and, with the aim of ensuring accessibility to research, lifts the embargo and all copyright restrictions from articles two years from publication. It is our hope that a two-year embargo will become an accepted standard for “green” publishing. Eight years ago we concluded in an Editorial that “continuous improvements in quality, relevance, speed, and accessibility are needed to maintain the interest of future authors and subscribers” (14). At that time, we initiated a development strategy for the Journal that, compared to 2008, has almost doubled the impact factor (from 1.820 to 3.454), shortened greatly the average publication time, and increased accessibility through the rapid online publication and the promotion of OA. While the development of the journal continues to evolve, our focus today is on maintaining our high quality by extending and sharpening the Journal’s editorial expertise, the basic foundation of which is an active Editorial Board. In addition, our new strategic goal, is to be more open. Not only in terms of accessibility and increased free content, but also with respect to new authors and ideas, and members of NOROSH. We hope you will continue to support us on this journey as we navigate the unpredictable seas of academic publishing. We welcome your feedback and suggestions on how we can better serve all our stakeholders.

OBJECTIVES: Epidemiological studies suggest that long working hours and shift work may increase the risk of chronic diseases, but the “toxic” elements remain unclear due to crude assessment of working time patterns based on self-reports. In this methodological paper, we present and evaluate objective register-based algorithms for assessment of working time patterns and validate a method to retrieve standard payroll data on working hours from the employer electronic records. METHODS: Detailed working hour records from employers’ registers were obtained for 12 391 nurses and physicians, a total 14.5 million separate work shifts from 2008–2013. We examined the quality and validity of the obtained register data and designed 29 algorithms characterizing four potentially health-relevant working time patterns: (i) length of the working hours; (ii) time of the day; (iii) shift intensity; and (iv) social aspects of the working hours. RESULTS: The collection of the company-based register data was feasible and the retrieved data matched with the originally published shift plans. The transferred working time records included

Working hours play a crucial role in the life, health, and well-being of workers. Concerning irregular working hours, the recent Fifth European Working Conditions Survey (1) shows that night work is carried out by 19% and shift work by 17% of all workers in Europe. More than half of the total workforce works at least one day during the weekend and 21% works “on call”. The health effects of night and shift work have been a popular and important area of research within Scandinavian Journal of Work, Environment & Health (eg, 2–4), including new and interesting data and a consensus statement on shift work and breast cancer (5) published in this issue (5–8). As working times are becoming increasingly irregular and flexible, their associations with work–life balance, work satisfaction, mental health, and productivity are of growing interest. Regarding worktime flexibility, the literature distinguishes between company-based and employee-oriented flexibility (9–13). The former refers to “the need of employers to extend, modify, or reduce work hours according to client or production needs” (10, p503). Shift work and mandatory overtime are well-known examples. Employee-oriented worktime flexibility refers to autonomy regarding working times with the aim of meeting employee needs (14). A similar construct is worktime control (WTC): “an employee’s perception of his/her possibilities to control the duration, position, and distribution of his/her working times” (10, p503). WTC refers to self-determination of worktime aspects such as starting and ending times of the work day, breaks, days off, vacations (9), and control over whether, when and how much to work overtime (15). The distinction between company-based and employee-oriented worktime flexibility is helpful but one must bear in mind that a clear distinction is not always possible: although scholars tend to present WTC as a form of employee-oriented flexibility, it may also be implemented to advance organizational needs, such as higher work motivation and productivity and lower absenteeism and turnover of valued employees (16). Applications of worktime flexibility are by no means new phenomena. Company-based shift work has been a health issue in Europe since the end of the 19th century (17). WTC was pioneered at a German company in 1967, in the form of “gliding time” (cf. flextime). This early experiment resulted in favorable organizational outcomes and, from 1970 onwards, flextime spread in West-European countries (18). Yet, until the late 20th century, patterns of work schedules remained quite uniform, and work hours were still mainly determined by the employer with limited freedom on the part of employees (11, 18). During the 1990s, major trends towards enhanced employee-oriented WTC emerged. This was a reaction to the louder call for “healthy work” and the rising labor participation of women and associated challenges regarding successfully combining work and family (11). In the 21st century, the trend towards more flexible worktime practices continues. Many organizations aim at flexible worktime arrangements that combine company-based and employee-oriented flexibility. An interesting example of a relatively new and intense flexible worktime intervention is self-scheduling, mostly applied in shift work settings. The employer defines the number of workers needed for several specific time units (eg, for each hour of each working day over a specific time period) and employees can then choose their own working hours by signing up for specific time units, thereby taking into account their personal preferences, worktime regulations, and the minimum number of work hours they have to work according to their contract. Another flexible worktime practice that has gained popularity is “boundaryless work” – also known as “trust hours” (13) – which basically combines intensive employee WTC and spatial flexibility among white-collar workers. As a consequence, the traditional work day characterized by 8 hours of work, 8 hours of free time, and 8 hours of sleep, might be replaced by a different time structure in which work and private life are much more integrated. A well-known symptom of such integration is that many contemporary workers stay in contact with work during evenings, days off, weekends, and vacations, which is in some cases even expected by their employers. Not only individual employers and employees are increasingly engaged in promoting employee WTC, also several European countries (eg, UK and Scandinavian countries) stimulate WTC by introducing national legislation that enables employees to request employee-oriented flexible working times (12). In The Netherlands, such legislation is currently proposed to be included in the Dutch Work Directive. All in all, these efforts at multiple societal levels have led to a considerable prevalence of employee WTC in many European countries. A recent international survey among 27 000 European companies showed that 57% of all European companies applied some type of flextime arrangement. This marks a vast increase over the 48% in 2004 (19). WTC is most prominent in North-European companies: 60–80% of all companies within Finland, Denmark, Sweden, UK, and Germany indulge flextime. It is less pronounced in East Europe [circa 33%; (19)]. Against this background, the Scandinavian Journal of Work, Environment & Health decided to publish a thematic issue on WTC. The aim is to provide an overview of current scientific knowledge about the effects of WTC on employee- and organizational outcomes and advance knowledge on the effects of self-scheduling. In this editorial, we briefly summarize relevant theoretical and empirical insights regarding WTC. We also introduce a research agenda. Theoretical insights and empirical findings on the effects of worktime control Theoretical groundings for the assumed benefits of increased WTC for both employees and organizations stem from several motivational and occupational health theories. From the perspective of Effort–Recovery Theory (20), WTC can be assumed to promote a favorable balance between effort and recovery as it stimulates internal recovery opportunities, by means of control over breaks, and external recovery, as employees can adjust their working and recuperation time to their current need for recovery. Three other key occupational health theories [ie, Self-Determination Theory (21), the Job Characteristics Model (22), and the Job Demands-Control Model (23)] suggest that WTC – as a subdimension of general autonomy – may stimulate worker motivation, health, and performance, and may prevent stress, absenteeism, and turnover. WTC can influence these outcomes by means of at least two processes: (i) through the actual utilization of WTC and associated change in working times and related work characteristics; and (ii) the mere opportunity to self-determine working hours may stimulate favorable outcomes, irrespective of an actual change in working times (this could be called a “psychological process”). Finally, based on theories of work–home interaction (24), WTC can be expected to advance a better work–non-work balance (and thus prevent stress), as WTC enables the adjustment of working time to meet obligations, needs, and activities in private life. Following such theoretical insights, Baltes and colleagues (16) decided to empirically substantiate whether flextime interventions indeed stimulate favorable organizational outcomes. In a meta-analysis of 27 intervention studies, these authors concluded that flextime (ie, employee control over starting and ending times of the work day) can have positive effects on organizational outcomes (ie, productivity, job satisfaction, absenteeism, and satisfaction with work schedule). However, differences in effect sizes were found, indicating that flextime is more likely to impact attendance (absenteeism) than directly impact worker effectiveness (productivity). In the first contribution of this thematic issue, Nijp and colleagues (15) build upon this meta-analysis. They systematically review the scientific literature – published between 1995 and 2011 – on the association between the broad concept of WTC on the one hand (general as well as several specific aspects of WTC, eg, flextime and leave control) and employee- and organizational outcomes on the other. Their review shows that there is (moderately) strong evidence for a positive association between WTC and work–non-work balance. Moreover, there are indications for favorable associations with indicators of health, well-being, and job-related outcomes, but more longitudinal and intervention research is needed to draw definite conclusions about causal effects. Contemporary knowledge on the effects of self-scheduling was discussed in a recent Cochrane review on flexible working conditions (12) and within the review by Nijp and colleagues (15). The scarce empirical research in this field provides mixed findings. In some studies, for some health-related outcomes, significant changes were found after the introduction of self-scheduling [eg, significant decrease in systolic blood pressure (25) and in tiredness during the night shift (26), and a favorable change in work–life balance and job satisfaction (27)]. For other outcomes or within other studies, no significant changes were reported after implementation of self-scheduling [eg, no significant changes in diastolic blood pressure and sleepiness (25), mental health (26), somatic symptoms (27), stress, work–family conflicts, and biomarkers of cardiovascular disease (28), or sleep (29)]. Based on these findings, the authors of both reviews cautiously conclude that the introduction of self-scheduling can have favorable effects, but more intervention research is urgently needed to understand fully the effects of different types of self-scheduling on distinct outcome categories (12, 15). The current thematic issue contains two studies on self-scheduling (30, 31) that present valuable new insights into the process factors behind self-scheduling and changes in work and well-being characteristics following the introduction of self-scheduling. For now, it seems safe to conclude that WTC has the potential to enhance health, well-being, work–non-work balance, and organizational outcomes. Yet, experts emphasize many limitations of previous research and gaps in knowledge that need to be addressed to understand fully under what circumstances WTC interventions (eg, self-scheduling) will result in favorable employee and organizational outcomes. A research agenda Initiate research with proper designs: The majority of previous WTC studies applied a cross-sectional design (cf. 15). As the limitations of cross-sectional studies with respect to causal inferences are well-recognized, our first appeal is to conduct more well-designed intervention studies on WTC. The current popularity of WTC applications in organizations creates a window of opportunity for researchers to look into such natural experiments. Since methodological rigor stimulates more valid causal inferences, intervention research should build upon a proper study design (at least pre- and post-measurements of central study variables and comparison of experimental and control groups over time). As previous intervention research suggests that health and organizational effects of increased WTC may diminish over time (16), intervention studies should not only assess short-term effects (eg, 1–6 months after the intervention) but also evaluate longer-term impact. As we encourage WTC researchers to apply an intervention design, we formulate five suggestions with respect to the content and focus of future WTC intervention research. Assess whether there is a need for the intervention: Prior to any intervention, researchers should establish whether there is need for change. This needs-assessment should be twofold. First, one should assess whether pre-intervention levels of WTC, health, and/or well-being are low in absolute terms. In this regard, we advise to not merely apply a general assessment of available WTC but rather to examine the present level of multiple subdimensions of WTC [eg, control over starting and ending times of the workday, overtime, days off, breaks, and the entire work schedule; cf. (11)]. Second, there should also be a pre-intervention assessment of the subjective individual need for higher levels of each subdimension of WTC, ie, regardless of the absolute level of WTC, researchers should assess whether employees are satisfied with the current level of WTC. If either of these assessments confirms a need for change, a WTC intervention is warranted. Study the intervention content: For a valid understanding of the potential health and organizational effects after a WTC intervention, researchers must portray the precise content of the worktime control intervention (ie, describe what was planned and what actually happened). It is an illusion to believe that there is only one type of self-scheduling, flextime, or boundaryless work, and – as such – it is necessary to elucidate the specific characteristics of any intervention. This will help to establish what type of WTC intervention ascertains the most favorable effects. Related to this, it is also crucial to examine whether the applied WTC intervention indeed elicits a change in WTC [ie, manipulation check: comparison of pre- and post measurements of WTC; cf. (26, 28, 29)]. After all: a specific WTC intervention can be theorized to stimulate WTC, but this may not be evident in practice [cf. program failure (32)]. For example, one of the studies of this special issue indeed shows that self-scheduling individuals reported only moderate average scores on WTC and that personal fit (ie, the association between preferred and actual work hours) was present but not large in magnitude (30). Regarding the post-intervention assessment of WTC, we advise researchers also to assess to what extent employees actually use their possibilities to self-determine working times and consequently change their actual working times. This assessment may provide more insight into the mechanisms behind the potential association between WTC and health-related or organizational outcomes (ie, “actual usage and change in work hours” versus “the psychological effect of the mere availability of WTC”). Both processes include higher perceived autonomy over working times, but assessment of actual utilization of WTC may show which mechanism is more prominent. One could imagine that for some outcome variables (eg, work–non-work balance), actual utilization is most important, whereas for other outcome variables (eg, work motivation) having the possibility to change working times is sufficient to establish beneficial effects. Assess the intervention process: Intervention effects are not only determined by the intervention content but also by the way it is implemented, designed, and managed [process-related factors; (33, 34)]. Many previous intervention studies do not provide insight into process factors and therefore little is known on the implementation process, contextual factors, and the aim and rationale for interventions (12). Yet, ignored process factors may have an important influence on the effects of an intervention. For instance, employees’ attributions about the aim of a human resource practice (in this case: a WTC intervention) may be of great significance to employee attitudes towards the intervention (eg, in terms of resistance to change) and may partly determine organizational performance after the implementation (35). Future intervention research should therefore include information on process factors, such as: (i) the aim of the intervention and employees’ attributions of the aim; (ii) the steps that were undertaken to introduce the intervention; (iii) the level of organizational, supervisory, and employee support (or resistance) regarding the intervention; and (iv) whether supervisors and/or employees were trained to learn how to apply the new work method or related software, etcetera. Knowledge about the content and process factors of a WTC intervention will help to establish not merely whether a WTC intervention is effective, but under what specific circumstances a specific WTC intervention is effective for which specific outcome variables (36). Perform subgroup analyses: Only examining overall effects for all employees may obscure subgroup effects and may lead to an erroneously pessimistic conclusion about the effectiveness of WTC interventions. Favorable effects of an increase in WTC may be most (or even only) evident among workers who experience problems with their pre-intervention health or working hours (eg, the group with high need for WTC). It can be hypothesized that especially employees with relatively high obligations in private life (eg, parents of young children) and employees with a higher need for recovery (eg, some subgroups of older or chronically ill employees) may benefit most from increased WTC. In line with this, previous research found WTC to be mostly beneficial for women who combined fulltime employment with long domestic working hours (37–39). Regarding subgroup analyses, we also advise to elucidate the percentage of workers that experienced a change in WTC and compare these change groups with stable (low and high) WTC groups regarding indicators of well-being, health, and performance over time [cf. (40, 41)]. Avoid a biased focus on positive effects: Traditionally, occupational health research shows a biased focus on adverse consequences of work (42). It is encouraging to see that previous WTC research has focused on potential favorable outcomes. Yet, a caveat is in place: a one-sided focus on “only” positive effects may conceal that applications of WTC may also entail negative side-effects on psychosocial- and time-related work characteristics (36). For instance, self-scheduling can be hypothesized to result in a better work–non-work balance (as employees can adjust their working times to their responsibilities in private life), but it may also result in more “unhealthy work schedules”. The common organizational practice of “better pay for unhealthier work shifts” may stimulate some employees to prefer long sequences of night shifts or many weekends in a row. In this respect, it is good to learn that Garde et al (31) demonstrate that the implementation of self-scheduling did not compromise general recommendations for “healthy shift work design”. Nevertheless it is important that researchers pay attention to potential “unhealthy” choices and the role of related changes in pay level and financial incentives. Also, from a primary prevention point of view, self-scheduling software should be designed in such a way that unhealthy choices are prohibited. In the paper by Ingre and colleagues (30) also other potential problems associated with self-scheduling are identified: (i) lower predictability and regularity in work hours that challenge successful integration of work and private life (especially if preferred rosters are not granted); (ii) competition and conflicts among colleagues for the “best shifts” (with the risk of less assertive employees always losing the battle), and (iii) well-established work teams being shattered by the new individualistic scheduling. Anecdotal evidence shows that implementation of boundaryless work not only implies more WTC and spatial flexibility, but frequently also an emphasis on performance management and virtual contact possibilities. Specifically this combination of work characteristics may result in higher job demands and overtime work (13), less time for recovery, and more difficulties with psychological detachment from work. Spatial flexibility may also imply less optimal work ergonomics and a possible risk for musculoskeletal problems and repetitive strain injury among computer workers. These examples emphasize the need for a balanced evaluation of potential positive and potential negative effects of WTC applications on the work environment and on health and performance. Thematic issue Considering the recommendations above, we believe that the topic of WTC and its many applications to be a fruitful ground for at least another decade of research. With the current thematic issue, we aspire to make a valuable contribution to the contemporary knowledge and literature. As such, this issue starts with a systematic review study on the association between WTC and employee as well as organizational outcomes (15), followed by two studies on the practice of self-scheduling (30, 31). After reading this thematic issue, we hope that researchers will be inspired to initiate high quality research on the topic of WTC and working time in general, as this research will not only have a clear theoretical and empirical contribution, but may also help employees, employers, and organizations in practice.

OBJECTIVE: The occurrence of possible health hazards among former shift workers is not well-known. We studied associations of former and current shift work with the metabolic syndrome (MetS). METHODS: Participants were 1811 full-time employees of a large airline company (1009 men). Working times were categorized into five groups: day worker [N=297 (the reference group)], former shift worker (N=341), 2-shift worker (N=418), night-shift worker (N=283), and in-flight worker (N=472). MetS was measured by the International Diabetes Federation (IDF) criteria and the National Institute of Health Adult Treatment Panel III (NCEP) guideline. The prevalence of the syndrome in the study population was 28.5% and 20.8%, respectively. RESULTS: Among male former shift workers, MetS was more prevalent compared to male day workers [IDF: age-adjusted odds ratio (OR) 2.13, 95% confidence interval (95% CI) 1.35–3.37; NCEP: OR 1.83, 95% CI 1.13–2.96]. Associations did not change after additional adjustments for education, smoking, physical activity, alcohol consumption, and insomnia symptoms (IDF: OR 2.00, 95% CI 1.26–3.19; NCEP: 1.67, 95% CI 1.02–2.72). Male 2-shift workers also had an elevated risk of IDF-defined MetS (OR 1.64, 95% CI 1.06–2.55) but the association weakened in the fully adjusted analyses (OR 1.48, 95% CI 0.93–2.24). Prevalence of the MetS was marginally significantly higher among night-shift work (IDF: OR 1.51, 95% CI 0.95–2.34) and was attenuated further with additional adjustments (OR 1.37, 95% CI 0.84–2.22). Among women, no significant differences in prevalence of the MetS between day work and shift work were observed. CONCLUSION: Findings of the cross-sectional study suggest that MetS diagnosed by standardized criteria is more prevalent among former male shift workers than current day workers who have never worked in shifts.

In 2007, the International Agency for Research on Cancer classified shift work involving circadian disruption as probably carcinogenic to humans (group 2A), primarily based on experimental and epidemiologic evidence for breast cancer. In order to examine options for evidence-based preventive actions, 16 researchers in basic, epidemiological and applied sciences convened at a workshop in Copenhagen 26–27 October 2011. This paper summarizes the evidence from epidemiological and experimental studies and presents possible recommendations for prevention of the effects of night work on breast cancer. Among those studies that quantified duration of shift work, there were statistically significant elevations in risk only after about 20 years working night shift. It is unclear from these studies whether or not there is a modest but real elevated risk for shorter durations. Hence, restriction of the total number of years working night shift could be one future preventive recommendation for shift workers. The diurnal secretion of melatonin by the pineal gland with peak in secretory activity during the night is a good biochemical marker of the circadian rhythm. Disruption of the diurnal melatonin secretion pattern can be diminished by restricting the number of consecutive night shifts. Reddish light and reduced light intensity during work at night could potentially help diminish the inhibitory activity of light with strong intensity on the melatonin secretion, but further mechanistic insight is needed before definite recommendations can be made. Earlier or more intensive mammography screening among female night shift worker is not recommended because the harm–benefit ratio in this age group may not be beneficial. Preventive effects of melatonin supplementation on breast cancer risk have not been clearly documented, but may be a promising avenue if a lack of side effects can be shown even after long-term ingestion. Women with previous or current breast cancer should be advised not to work night shifts because of strong experimental evidence demonstrating accelerated tumor growth by suppression of melatonin secretion. Work during the night is widespread worldwide. To provide additional evidence-based recommendations on prevention of diseases related to night shift work, large studies on the impact of various shift schedules and type of light on circadian rhythms need to be conducted in real work environments

In many developed countries, policies are enacted to increase labor force participation among older workers and to extend the age of statutory retirement in response to the ageing of society. Within Europe, the employment rate among 55–65-year olds has increased in the past decade, but there are large differences among countries, for example, reported participation among men varies from 41% in France to 73% in Sweden (1). Hence, in most countries, it will already be a large societal challenge to support workers to maintain their ability to work until the age of 65. The increase in the statutory retirement age to 67 years and beyond will require additional societal efforts to ensure that older workers can continue to contribute to a productive workforce. Work-related disability is one of the most important routes of displacement from the labor market (2). Recent articles have addressed a variety of work-related factors that have increased the risk of disability pension (3–5). This particular use of the term “disability pension” demonstrates that this exit route from paid employment has dramatic consequences for most workers: once out, always out. In this thematic issue of the Scandinavian Journal of Work, Environment & Health, several articles address the causes and consequences of work-related disability and target prevention strategies. Clearly, aging at work and disability will remain an important research area in the foreseeable future. Two linked publications have studied sickness absence and disability pension patterns in a large cohort of public-sector employees across different towns and regions in Finland. The first study addresses current concerns about higher flexibility in labor contracts by investigating whether temporary contract workers differ from those with a permanent contract with respect to prolonged sickness absence and disability pension for depression (6). Temporary employment predicted longer duration of prolonged sickness absence (4–12 months), especially among the lower educated and older workers, but had no influence on onset and recurrence. This finding (ie, return to work was faster among those with a permanent employment) raises important questions about the current labor market: Is there sufficient institutional support for temporary employees? Are employers less willing to hire temporary employees with depressive symptoms? Is there less access and lower quality of rehabilitation programs for temporary employees? These questions urgently need answers given the rapid growth in flexible labor contracts in most countries. The related study by Juvani and colleagues (7) reported that – during a mean follow-up of almost 9 years – about 8.9% of employees were granted a disability pension, primarily for musculoskeletal diseases (43%) and depression (19%). Effort–reward imbalance, estimated at work-unit level, was a strong risk factor for disability due to depression but did not influence disability due to musculoskeletal diseases. Clear inequalities across the workforce were present. Civil servants in the highest occupational class reported the highest efforts at work, but rewards were balanced accordingly. Employees in the lowest occupational classes suffered from the lowest rewards and highest imbalance between efforts and rewards and were most at risk for premature displacement from the labor market due to depression disability (7). Since a considerable part of disability pensions was granted to employees below the age of 50 years, the consequences for working careers must have been large in this study population. In the Norwegian disability register, those persons with a benefit for a mental disorder lost approximately 19 working years before the age of 65 years (8). Järvholm and colleagues demonstrated the substantial consequences of becoming too disabled to remain in the workforce (9). In a large construction cohort with almost 30 years of follow-up, profound differences were observed among 22 occupational groups for risk of disability pension, varying from a relative risk (RR) of 2.16 for rock workers to 0.54 for salaried workers compared to the reference group comprised of electricians. This 4-fold difference was reflected in working years lost due to disability pension before the age of 65 within these occupational groups: 3.2 years for rock workers, 1.4 years for electricians, and 0.7 years for salaried workers. Most working years were lost after the age of 50, predicting that an increase of the statutory retirement age from 65 to 67 years will imply that in some occupational groups a substantial part of all workers will spend these additional years in disability. These occupational differences in the risk of disability pension will increase socioeconomic inequalities in the population. The longitudinal register-based study in the Finnish workforce shows that manual workers are at increased risk for disability pension compared to upper-class, non-manual workers with a RR of 2.79 and 2.29 among men and women, respectively. Disability due to musculoskeletal disorders and cardiovascular diseases contributed most to the observed socioeconomic differences (10). This study again raises the question whether it is a fair policy to increase the statutory retirement age regardless of the strenuous jobs performed. Disability is primarily investigated for causes and consequences in observational studies. There are very few experimental studies on primary and secondary preventive interventions. Sundstrup and colleagues developed a specific strength training for upper-extremity muscles for slaughterhouse workers suffering from upper-extremity chronic pain (11). This occupational group is notoriously known for repetitive and high-force activities and consequent onset of various musculoskeletal disorders and associated work-related disability. The individual strength training was compared to the usual-care ergonomic training approach for impact on self-reported work ability. After ten weeks, a relative difference of 6% in work ability was observed, primarily caused by a strong deterioration in work ability in the usual-care group and a slight improvement in the strength-training group. Hence, the intervention shows some promising short-term benefits, but its ability to contribute to the prevention of long-term displacement from paid employment due to disability remains to be seen. The studies on work-related disability in this issue of the Scandinavian Journal of Work, Environment & Health clearly demonstrate the importance of disability as a major cause of lost working years in the workforce. The studies present evidence that disadvantaged groups in society suffer most from strenuous working conditions and resulting work-related disability. With growing pressure to work later in life, it is paramount to support the ability of these workers to continue working. Recently, 14 European countries and Canada launched a research program “More Years, Better Lives: Strategic Research Agenda on Demographic Change” (12). The research agenda has a particular focus on areas that can inform policy and includes economic and social production and ways they could be maintained in a sustainable manner across the extended lifespan. The agenda emphasizes the implications of greater diversity, not only in relation to aging and work ability but also in the labor market due to increasing socioeconomic differences and new economic trends such as the growing unpaid and informal work market. The research agenda confirms that there is need for both etiological and intervention research on new models for disability prevention and reintegration among both young and aging workers. The interventions should especially consider increased diversity and socioeconomic differences at work. The incentive for promoting working life among older workers is clearly there, but until now surprisingly little is known about what programs and policies are needed. The prevalence of disease is high among older workers, for example a recent Finnish study found that 74% of municipal employees had a chronic disease at the age of around 60 (13). Should workers in strenuous jobs try to find other employment? Should employers tolerate a worker with one or several chronic diseases? Most studies focus on individual factors of reduced work ability or loss of paid employment, such as the imbalance between job demands and personal capabilities and unhealthy behaviors, whereas societies and employers will also strongly determine older workers’ inclusion in the workforce. These contextual factors are considerably less-well studied and may provide crucial information on necessary actions to increase the participation of older workers in working life. This societal challenge requires active contributions from workers, employers, and governments.

In order to establish a causal relation between shift work and cardiovascular disease (CVD), we need to verify the pathways from the former to the latter. This paper aims to review the current knowledge of the mechanisms between shift work and CVD. Shift work can increase the risk of CVD by several interrelated psychosocial, behavioral, and physiological mechanisms. The psychosocial mechanisms relate to difficulties in controlling working hours, decreased work–life balance, and poor recovery following work. The most probable behavioral changes are weight gain and smoking. The plausible physiological and biological mechanisms are related to the activation of the autonomic nervous system, inflammation, changed lipid and glucose metabolism, and related changes in the risk for atherosclerosis, metabolic syndrome, and type II diabetes. The data provide evidence for possible disease mechanisms between shift work and CVD, but compelling evidence on any specific mechanism is missing.

Practical tips for good sleep are a popular topic in monthly published magazines and tabloids. Despite the plethora of good advice, normal sleep length has been mostly on the decline during the past three decades, with sleep quality among the work-aged population decreasing the most (1–3). In addition to long working hours, work stress and shift work are among the primary culprits for the increase of sleep problems among the world’s workers. In this issue of the Scandinavian Journal of Work, Environment & Health, a systematic review examines the association between psychosocial work characteristics and sleep quality (4). While earlier research has often been cross-sectional and predominantly focused on work stress (5, 6), the current review took on the demanding task of analysing only longitudinal and intervention studies. The review is also valuable in its analysis of both the normal and reversed relations and its creation of valuable quality criteria for future studies on psychosocial work characteristics and sleep. Based on the review, consistent and strong evidence exists for a negative relationship between job demands and sleep quality as well as a positive relation between job control and sleep quality. However, the number of reviewed studies was too small to conclude on the association between other psychosocial work characteristics and sleep or the possible reversed relationship of sleep quality and work characteristics. Considering the extensive evidence on the association of psychosocial work characteristics, work stress and sleep, the detection of only three high-quality longitudinal studies and a single high-quality intervention study from the original 2397 papers is most surprising. This is partly explained by the inclusion criteria applied and the strict quality criteria related to the study design, the validity of exposure and outcome measures, and the statistical analysis. However, none of the reviewed studies used objective sleep recordings although sleep quality was investigated validly by questionnaires in the high-quality studies. Jackowska et al (7) recently studied the role of psychosocial factors and affective responses with the discrepancies between subjective and objective measures of sleep. While objective sleep efficiency (based on actigraph recording) was unrelated to variation in both psychosocial work characteristics and negative affect, self-reported poor sleep efficiency was more prevalent among those overcommitted or with lower level of social support at work (7). If the evaluation of both work characteristics and insomnia are based on subjective estimations, the findings of cross-sectional associations between the two are not surprising. However, based on the obvious discrepancies between subjective and objective analysis of sleep, longitudinal studies that may indicate a time-related change in subjectively reported sleep quality due to a change in psychosocial work characteristics may not have any effects on objectively recorded sleep. If the link between psychosocial work and sleep quality is limited to only subjective reports, it has implications for how the relationship should be interpreted. One interpretation is that the relationship is moderated by other variables like depressive symptoms or is related to reporting biases. Psychosocial work characteristics have been found to be associated with a moderate risk of coronary heart disease and some mental health problems (eg, 8, 9). Since disturbed sleep (based mostly on sleep length) is associated with several cardiovascular manifestations (eg, 10–12), and there are also potential mechanisms between the two based on experimental sleep restriction studies (eg, 13, 14), it would be interesting to know whether disturbed sleep due to work stress or unfavorable psychosocial work characteristics could be a pathway from work stress to cardiovascular diseases (15). It is possible but not plausible. First, the present review (2) indicates that effects sizes for work demands and job control in relation to sleep quality were only small to moderate based on the fully adjusted models. Second, the material did not allow for a qualitative estimation of the magnitude of the effects on sleep length. Studies measuring only sleep length were even excluded due to the focus on perceived sleep. Sleep follows a homeostatic regulation with the ability to adapt to small changes in sleep quality. Work stress is typically associated with increased sleep latency due to work rumination (5). It is also the degree of sleep deprivation – not the degree of perceived sleep quality – that correlates best with the biological and metabolic changes (16). The majority of the current knowledge on the association of sleep with health is still based on sleep length (10–12) even though the number of epidemiological studies on the association of sleep quality and health continues to increase (17). Although sleep quality correlates with short sleep in the general population (18), the effects of unfavorable psychosocial work characteristics on sleep length among healthy subjects may only be minor. We recently studied the association of work stress with insomnia using both subjective and objective analysis of sleep (19, 20). The shift-working women were recruited from hospital wards that belonged to either the top or bottom job strain quartiles of the Job Content Questionnaire. High job strain was associated with difficulties initiating sleep (probably due to work rumination) and reduced psychomotor vigilance during the night shifts, but the average objective sleep duration and sleep efficiency did not differ between the groups. A detailed analysis of the working hours showed that the job strain-related differences in sleep and recovery were mostly attributable to differences in shift arrangements. While the sleep curtailment due to work stress was only 16–28 minutes during the working days, sleep length varied up to 2 hours due to changes in work shifts (18, 19). In the second paper of this issue, Garde et al (21) examined if sleep duration is a risk indicator for ischemic heart disease (IHD) and all-cause mortality, and how perceived stress during work and leisure time and the use of hypnotics modified the association. As expected, short sleep (

The increasing societal costs of the expanding retired population are forcing industrialized countries to find new ways to extend life-long work careers. Work careers can be extended in the beginning, middle, or end of the traditional working life, utilizing solutions on the borders of main-life transitions between education, labour market, unemployment, disability, private household, and old age pension. While the central political debate focuses on pressures to delay the general retirement age and the development of economic incentives, policymakers are also interested in increasing participation in working life through disability prevention (1). A critical prerequisite for the extension of work careers both before and after the retirement age is that the employee has sufficient work ability. Work ability is often conceptualized as the balance between work and personal resources and can be measured by the work ability index (WAI) (2). When measured by WAI, work ability is highly predictive of future disability, sickness absence, health, and even the mortality of workers (3–5). But are employees able to maintain their work ability until the retirement age? And could those who are, work even longer? In OECD countries, the primary diagnostic causes for disability retirement are musculoskeletal diseases and mental disorders (1). According to the report, about 6% of the working-age population rely on disability benefits. Until the recent recession struck the labor market in 2008, disability was even more prevalent than unemployment across the different OECD countries and spending on disability benefits was twice as high as spending on unemployment benefits (1). It was concluded that already with the current retirement age, too many workers leave the labour market permanently due to disability, and too few people with reduced work capacity manage to remain in employment. In this issue of the Scandinavian Journal of Work, Environment and Health, 28-year trajectories of work ability were studied among initially 44–58-year old municipal employees until old age (6). Work ability was assessed in four separate follow-ups as present perceived work ability relative to lifetime best. Among more than half of the women and nearly half of the men, work ability remained on a moderate-to-excellent level throughout the follow-up time, suggesting a possibility of being basically able to work even after the normal retirement age. The results were even more positive in a recent study of 20–65-year old managers (7). During ten years, work ability remained good or excellent among 88% of the subjects. But if about half of the workforce would be able to work after their normal retirement age, would they actually want to do so? In this issue, Nilsson et al (8) evaluated the factors behind why some older workers want to work until the age of 65 years or beyond while others leave the workforce earlier. As in the follow-up study of Bonsdorff et al (6), over half – 54% – of the participants stated that they could work beyond the retirement age but only 38% “wanted” to do so. The factors explaining willingness to work later related, first and foremost, to economic incentives, but also to family/leisure pursuits and societal, managerial, and organizational attitudes towards retirement and older workers. The essential role of economic factors in retirement has also been supported by earlier studies (9, 10). According to Bonsdorff et al (6), those who maintained their work ability on an excellent-to-moderate level throughout the long follow-up had reported less mental and physical work-related strain in midlife. The authors concluded that work strain may have far-reaching negative effects on individuals’ work ability from midlife to old age. The results are supported by similar observations where several physical and mental working conditions predicted future disability retirement (eg, heavy work, work in uncomfortable positions, long working hours, inability to control individual working hours, noise at work, inability to ­communicate with fellow workers, low job control, and insufficient social support from supervisors) (11, 12, 13). Also in this issue of the Journal, Leinonen et al (13) studied the association of disability retirement to socioeconomic position and working conditions. Based on a ten-year prospective study of municipal employees in Helsinki, there were large social class differences in disability retirement. In lower social classes, unfavorable physical working conditions appeared to be the primary reasons for disability retirement. For mental disorders, job control also mediated the association. There is now good evidence that low socioeconomic position is strongly associated with unfavourable working conditions and increases the likelihood of both psychiatric and musculoskeletal work disability and disability pensions (13–16). In general, work ability declines faster in physical than mental work (17). In construction work, for example, physical workload seems to be the critical determinant of work ability (18). However, even managerial position as such does not prevent the decline of work ability. The organizational climate, job control, and other specific work demands of managers were related to their work ability trajectories (7). We thus seem to know the main factors predicting disability, but do we know what really works in prospective settings? For example, good possibilities to control individual working times are associated with the reduced risk of early retirement in prospective cohorts (8), but do we know how to increase the individual control of working times in a feasible and sufficient way to delay the retirement age? Although, repetitive work demands predict disability (11), do we know feasible ways to decrease systematically physical workload in different work tasks? Unfortunately there is only scattered information available from intervention studies aimed at the prevention of disability in long-term settings (19). A promising alternative may be to analyze the effects of natural interventions on work ability. For example, based on a phone interview at baseline and one year later, construction roofers who had received job accommodation for musculoskeletal disorders had a four-time lower risk for retiring compared to workers with a similar medical status but no accommodation (20). Research is needed on practical and feasible ways to modify the work demands at both the individual and corporate level. To get feasible information, studies need to be carried out in different industrial sectors but especially in occupations where physical work is required. Work ability is the balance between work and personal resources. The challenge of disability prevention is related to the ability to create healthy and satisfying work conditions. Although effective national- and corporate-level strategies supporting the promotion of well-being at work are needed, in addition to interaction between the worker, his or her supervisor, and the healthcare system, the prevention of disability always goes back to the worksite level. Musculoskeletal and mental disorders – the most important reasons for early retirement – are often associated with partial work disability. Working conditions and the work itself need to be modified and improved in such a way that sufficient work ability is maintained and people can and want to participate in working life.

Epidemiological studies have shown that short or insufficient sleep is associated with increased risk for metabolic diseases and mortality. To elucidate mechanisms behind this connection, we aimed to identify genes and pathways affected by experimentally induced, partial sleep restriction and to verify their connection to insufficient sleep at population level. The experimental design simulated sleep restriction during a working week: sleep of healthy men (N = 9) was restricted to 4 h/night for five nights. The control subjects (N = 4) spent 8 h/night in bed. Leukocyte RNA expression was analyzed at baseline, after sleep restriction, and after recovery using whole genome microarrays complemented with pathway and transcription factor analysis. Expression levels of the ten most up-regulated and ten most down-regulated transcripts were correlated with subjective assessment of insufficient sleep in a population cohort (N = 472). Experimental sleep restriction altered the expression of 117 genes. Eight of the 25 most up-regulated transcripts were related to immune function. Accordingly, fifteen of the 25 most up-regulated Gene Ontology pathways were also related to immune function, including those for B cell activation, interleukin 8 production, and NF-κB signaling (P

Shift-working nurses are exposed to a stressful work environment, which puts them at an increased risk for burnout and depression. We explored the effect of environmental stress on serotonin transporter gene (SLC6A4) promoter methylation among nurses from high and low work stress environments.Using bisulfite sequencing, we investigated the methylation status of five CpG residues of a CpG-rich region in the promoter of SLC6A4 by comparing female shift working nurses from a high work stress environment (n = 24) to low work stress environment (n = 25). We also analyzed the association of 5-HTTLPR polymorphism at 5' end of SLC6A4. Work stress was assessed by the Karasek's Model and possible signs of burnout or depression were measured by the Maslach Burnout Index General Survey and Beck Depression Index. Methylation levels were assessed by bisulfite sequencing of DNA extracted from peripheral blood leucocytes. Restriction enzyme treatment followed by standard PCR was used to identify 5-HTTLPR genotypes.We found that nurses in the high stress environment had significantly lower promoter methylation levels at all five CpG residues compared to nurses in the low stress environment (p

This study identifies the effects of sleep restriction and subsequent recovery sleep on glucose homeostasis, serum leptin levels, and feelings of subjective satiety. Twenty-three healthy young men were allocated to a control group (CON) or an experimental (EXP) group. After two nights of 8 h in bed (baseline, BL), EXP spent 4 h in bed for five days (sleep restriction, SR), followed by two nights of 8 h (recovery, REC). CON spent 8 h in bed throughout the study. Blood samples were taken after the BL, SR, and REC period. In EXP, insulin and insulin-to-glucose ratio increased after SR. IGF-1 levels increased after REC. Leptin levels were elevated after both SR and REC; subjective satiety remained unaffected. No changes were observed in CON. The observed increase of serum IGF-1 and insulin-to-glucose ratio indicates that sleep restriction may result in an increased risk to develop type 2 diabetes.

BACKGROUND: Sleep restriction, leading to deprivation of sleep, is common in modern 24-h societies and is associated with the development of health problems including cardiovascular diseases. Our objective was to investigate the immunological effects of prolonged sleep restriction and subsequent recovery sleep, by simulating a working week and following recovery weekend in a laboratory environment. METHODS AND FINDINGS: After 2 baseline nights of 8 hours time in bed (TIB), 13 healthy young men had only 4 hours TIB per night for 5 nights, followed by 2 recovery nights with 8 hours TIB. 6 control subjects had 8 hours TIB per night throughout the experiment. Heart rate, blood pressure, salivary cortisol and serum C-reactive protein (CRP) were measured after the baseline (BL), sleep restriction (SR) and recovery (REC) period. Peripheral blood mononuclear cells (PBMC) were collected at these time points, counted and stimulated with PHA. Cell proliferation was analyzed by thymidine incorporation and cytokine production by ELISA and RT-PCR. CRP was increased after SR (145% of BL; p

Work careers have been extended in many countries by lifting up the statutory old-age retirement age. Since it has been estimated that only about half of the workforce maintain work ability on a moderate level after some 63–65 years (1, 2) the discussion on an appropriate statutory retirement age has increased focus on the possible health effects of the transition to retirement. The discussion on possible changes in mental health has been especially interesting. Several recent prospective studies on workers’ mental health trajectories prior and after transition to retirement seem to suggest that retirement could be beneficial for mental health (3–5), but the evidence is not consistent. In this issue of the Scandinavian Journal of Work, Environment & Health, Laaksonen et al (6) examined trajectories of mental health five years before and five years after both old-age and disability retirement using data on purchases of psychotropic drugs. The study included all employees from the City of Helsinki who had retired between 2000–2008. This new study is novel compared to earlier studies due to the examination of the association of mental health to both old-age retirement as well as permanent, partial, and temporary disability retirement. Also, the use of different psychotropic drug types at 3-month intervals was used as an objective indicator of time-related changes in mental health. The results show that old-age retirement was unrelated to purchases of psychotropic drugs, but there was a constant increase in the use of these drugs with no clear change at the time of the retirement. Among disability retirees, psychotropic medication increased steeply before retirement. After disability retirement, purchases of antidepressants decreased slightly, while those of hypnotics and sedatives increased. The changes were largest among those who retired due to mental disorders and among non-manual employees. The steep increase in antidepressant use before disability retirement, as well as the modestly decreased use of them after retirement is in line with the results published by Oksanen et al (5) from the Finnish Public Sector Study. A new finding is that the steepest increase in the pre-retirement use of psychotropic drugs took place among the temporary retirement group. In Finland, insurance companies require a test period of pharmacological treatment before allowing disability retirement. Up to now, no similar requirements have been made for work modifications or other workplace-related interventions. Since the use of psychotropic medication increased already some five years before disability retirement, there should be several years time to consider interventions other than pharmacological ones. Based on prospective studies, increases in job control, social support, and communication in the working place are promising candidates to decrease the risk for disability pension (7–9). However, intervention studies related to work-related factors to prevent mental disorders among aging workers are very few (10, 11). Based on the French GAZEL cohort, old-age retirement was associated with a substantial reduction in mental fatigue, depressive symptoms, and insomnia (3, 4). Similarly, the Finnish Public Sector Study reported a decrease in antidepressant use after retirement among old-age retirees (5). In the Laaksonen et al study, there was an overall steady increase in the purchases of all psychotropic drugs among old-age retirees consisting mainly of an increase in the use of hypnotics and sedatives and no change in the use of antidepressants. The discrepancies between the studies are rather surprising and are probably due to national or methodological differences. Some of the difference could be due to the age of the statutory retirees. The French statutory retirees were almost 10 years younger – 72% were 53–57 years – while the old-age retirement age in the two Finnish studies was normally 63–65 years. The subjects of the two Finnish studies represent municipal workers, and the samples are thus rather similar. However, data on the use of medication in the Laaksonen et al study (6) was collected from a later period (2000–2008) than the Oksanen et al study (5) (1994–2005). The latter also required the use of ≥30 daily doses in each year in order to classify the use of antidepressant. Laaksonen et al (6) had a more sensitive measure for the use of the drugs by simply calculating the mean use of different type of psychotropic drugs during each of the 3-month intervals. The use of sedative antidepressants increased rapidly in Finland from 1999–2009 (12), and there has also been an increasing tendency to use smaller amounts of antidepressants for insomnia and anxiety disorders. It is thus plausible that the generally increased use of antidepressants in Finland could explain the non-decreasing steady trend in the use of antidepressants in the later study of Laaksonen et al (6). Nevertheless, the results suggest that it is not always true that old-age retirement is beneficial to mental health. This obviously depends on work and health-related factors, disability retirement being most often beneficial for workers with mental disorders. In some cases, the workplace can be a valuable resource-building environment for mental health (13).