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The article presents the discussion on evaluating effects of night and shift work patterns on type 2 diabetes (T2D) and hypertension in a longitudinal study. Topics include Hazard ratios (HR) and confidence intervals (CI) were estimated by discrete-time proportional hazard models, adjusting for sex, age, country of birth, and profession; and potential mechanisms linking night and shift work to diabetes and hypertension.

OBJECTIVE: This study aimed to investigate the effect of vitamin D deficiency on metabolic syndrome among shift workers. METHODS: This study included 207 756 workers who underwent a comprehensive health examination at a large South Korean university hospital between 2012 and 2018. We performed multivariate-adjusted logistic regression analysis and analyzed mediation and exposure-mediator interaction. RESULTS: Overall, 5.5% of the participants had metabolic syndrome. Compared to day work, the odds ratios (OR) of metabolic syndrome and vitamin D deficiency (

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.

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 nonnight workers) increased IHD risk. Organizing work schedules to minimize these exposures may reduce IHD risk. [ABSTRACT FROM AUTHOR]

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.

OBJECTIVE: The aim of this study was to investigate whether night work expressed by number and duration of night shifts, number of consecutive night shifts, and number of quick returns during the first 20 weeks of pregnancy is a risk factor for hypertensive disorders of pregnancy (HDP). METHODS: The study population comprised Danish workers in public administration and hospitals who gave birth between 2007 and 2013. Exposure was assessed objectively through payroll data. Information on the outcome was retrieved from the National Patient Register. We performed logistic regression on the risk for HDP according to night work adjusted for age, body mass index (BMI), parity, socioeconomic status, and sickness absence prior to pregnancy. RESULTS: Among 18 724 workers, 60% had at least one night shift during the first 20 weeks of pregnancy. The prevalence of HDP was 3.7%. Among night workers, the risk of HDP grew with increasing number of consecutive night shifts [odds ratio (OR) 1.41, 95% confidence interval (CI) 1.01–1.98) and of quick returns after night shifts (OR 1.28, 95% CI 0.87–1.95). Among obese women (body mass index ≥30 kg/m^2), those who worked long night shifts and longer spells of consecutive night shifts, and had the highest number of quick returns after night shifts, had a 4–5 fold increased risk of HDP compared to day workers. CONCLUSION: Working consecutive night shifts and quick returns after night shifts during the first 20 pregnancy weeks was associated with an increased risk of HDP, particularly among obese women.

OBJECTIVES: This study aimed to (i) compare odds of endometriosis in a cohort of flight attendants against a comparison group of teachers and (ii) investigate occupational risk factors for endometriosis among flight attendants. METHODS: We included 1945 flight attendants and 236 teachers aged 18–45 years. Laparoscopically confirmed endometriosis was self-reported via telephone interview, and flight records were retrieved from airlines to obtain work schedules and assess exposures for flight attendants. We used proportional odds regression to estimate adjusted odds ratios (OR_adj) and 95% confidence intervals (95% CI) for associations between exposures and endometriosis, adjusting for potential confounders. RESULTS: Flight attendants and teachers were equally likely to report endometriosis (OR_adj 1.0, 95% CI 0.5–2.2). Among flight attendants, there were no clear trends between estimated cosmic radiation, circadian disruption, or ergonomic exposures and endometriosis. Greater number of flight segments (non-stop flights between two cities) per year was associated with endometriosis (OR_adj 2.2, 1.1–4.2 for highest versus lowest quartile, P trend= 0.02) but block hours (taxi plus flight time) per year was not (OR_adj 1.2, 95% CI 0.6–2.2 for highest versus lowest quartile, P trend=0.38). CONCLUSION: Flight attendants were no more likely than teachers to report endometriosis. Odds of endometriosis increased with number of flight segments flown per year. This suggests that some aspect of work scheduling is associated with increased risk of endometriosis, or endometriosis symptoms might affect how flight attendants schedule their flights.

OBJECTIVES: Diabetes is a multifactorial disease of increasing prevalence. The literature suggests an impact of night work on metabolic components, though the relationship with diabetes is unclear. Our aim was to investigate gender-specific associations between night work and type-2 diabetes (DM2) or impaired glucose tolerance (IGT) using baseline data of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil). METHODS: The cohort comprised 15 105 civil servants, aged 35–74 years. Baseline assessments (2008–2010) included clinical and laboratory measurements and interviews on sociodemographic, occupational, and health characteristics. RESULTS: In the baseline sample (N=14 427), 19.6% were classified as having DM2 and 20.5% as having IGT. Mean age was 52.1 (SD 9.1) years. A total of 2041 participants worked at night for 1–20 years and 687 for >20 years. Among women exposed to night work for >20 years compared with no night work after adjustments for potential confounders, including obesity, the odds ratios (OR) derived from multinomial logistic regression for DM2 and IGT were 1.42 [95% confidence interval (95% CI) 1.39–1.45] and 0.96 (95% CI 0.94–0.99), respectively. Among men exposed to night work for >20 years compared with no night work, the OR for DM2 and IGT were 1.06 (95% CI 1.04–1.08) and 0.99 (95% CI 0.98–1.01), respectively. CONCLUSIONS: The association between years of night work and diabetes is stronger among women than men. Longitudinal studies from ELSA-Brasil will be able to corroborate or refute these findings.

OBJECTIVES: This study investigates whether different shift work schedules, compared to day work, are associated with need for recovery (NFR), future disability, and retirement intentions for employees employed within different economic sectors over the course of their careers. Shift work exposure duration and the healthy worker effect are also examined. METHODS: Data from the prospective Maastricht Cohort Study was used. Subsamples of industry (N=1877, all men) and healthcare (N=818, 624 women and 194 men) workers were separately investigated. GEE and Cox regression analyses were performed to investigate NFR longitudinally. Future disability was investigated using Cox regression, and retirement intentions were investigated using logistic regression analysis. RESULTS: Three-shift industry workers were at risk of becoming a case of elevated NFR during follow-up, compared to industry day workers. Three- and five-shift industry workers were at risk for future disability. In healthcare, irregular shift work was a risk factor for disability among older shift workers. No significant results were found regarding retirement intentions. Findings were probably an underestimation as exposure duration to shift work and the healthy worker effect affected the results. CONCLUSIONS: Shift work was associated with higher levels of NFR and a higher risk of disability. However, shift work is a multifaceted concept as different types of shift work schedules are differently associated with these outcomes. Different shift work types exist and shift work schedules allow for optimization, indicating that measures to prevent adverse outcomes should be tailored for different types of shift work and over the course of the work career.

OBJECTIVES: This study aimed to evaluate occupational exposures and menstrual cycle characteristics among nurses. METHODS: Using cross-sectional data collected in 2010–2012 from 6309 nurses aged 21–45 years, we investigated nurses’ menstrual function in the Nurses’ Health Study 3. We used multivariable regression modeling to analyze the associations between occupational exposures and prevalence of irregular cycles and long and short cycle lengths. RESULTS: The cohort reported cycle length as

Objective The aim of this study was to investigate whether night work expressed by number and duration of night shifts, number of consecutive night shifts, and number of quick returns during the first 20 weeks of pregnancy is a risk factor for hypertensive disorders of pregnancy (HDP). Methods The study population comprised Danish workers in public administration and hospitals who gave birth between 2007 and 2013. Exposure was assessed objectively through payroll data. Information on the outcome was retrieved from the National Patient Register. We performed logistic regression on the risk for HDP according to night work adjusted for age, body mass index (BMI), parity, socioeconomic status, and sickness absence prior to pregnancy. Results Among 18 724 workers, 60% had at least one night shift during the first 20 weeks of pregnancy. The prevalence of HDP was 3.7%. Among night workers, the risk of HDP grew with increasing number of consecutive night shifts [odds ratio (OR) 1.41, 95% confidence interval (CI) 1.01-1.98) and of quick returns after night shifts (OR 1.28, 95% CI 0.87-1.95). Among obese women (body mass index =30 kg/m2), those who worked long night shifts and longer spells of consecutive night shifts, and had the highest number of quick returns after night shifts, had a 4-5 fold increased risk of HDP compared to day workers. Conclusion Working consecutive night shifts and quick returns after night shifts during the first 20 pregnancy weeks was associated with an increased risk of HDP, particularly among obese women. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to (i) compare odds of endometriosis in a cohort of flight attendants against a comparison group of teachers and (ii) investigate occupational risk factors for endometriosis among flight attendants. Methods: We included 1945 flight attendants and 236 teachers aged 18-45 years. Laparoscopically confirmed endometriosis was self-reported via telephone interview, and flight records were retrieved from airlines to obtain work schedules and assess exposures for flight attendants. We used proportional odds regression to estimate adjusted odds ratios (ORadj) and 95% confidence intervals (95% CI) for associations between exposures and endometriosis, adjusting for potential confounders. Results: Flight attendants and teachers were equally likely to report endometriosis (ORadj 1.0, 95% CI 0.5-2.2). Among flight attendants, there were no clear trends between estimated cosmic radiation, circadian disruption, or ergonomic exposures and endometriosis. Greater number of flight segments (non-stop flights between two cities) per year was associated with endometriosis (ORadj 2.2, 1.1-4.2 for highest versus lowest quartile, P trend= 0.02) but block hours (taxi plus flight time) per year was not (ORadj 1.2, 95% CI 0.6-2.2 for highest versus lowest quartile, P trend=0.38). Conclusion: Flight attendants were no more likely than teachers to report endometriosis. Odds of endometriosis increased with number of flight segments flown per year. This suggests that some aspect of work scheduling is associated with increased risk of endometriosis, or endometriosis symptoms might affect how flight attendants schedule their flights. [ABSTRACT FROM AUTHOR]

Objectives Diabetes is a multifactorial disease of increasing prevalence. The literature suggests an impact of night work on metabolic components, though the relationship with diabetes is unclear. Our aim was to investigate gender-specific associations between night work and type-2 diabetes (DM2) or impaired glucose tolerance (IGT) using baseline data of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil). Methods The cohort comprised 15 105 civil servants, aged 35-74 years. Baseline assessments (2008-2010) included clinical and laboratory measurements and interviews on sociodemographic, occupational, and health characteristics. Results In the baseline sample (N=14 427), 19.6% were classified as having DM2 and 20.5% as having IGT. Mean age was 52.1 (SD 9.1) years. A total of 2041 participants worked at night for 1-20 years and 687 for >20 years. Among women exposed to night work for >20 years compared with no night work after adjustments for potential confounders, including obesity, the odds ratios (OR) derived from multinomial logistic regression for DM2 and IGT were 1.42 [95% confidence interval (95% CI) 1.39-1.45] and 0.96 (95% CI 0.94-0.99), respectively. Among men exposed to night work for >20 years compared with no night work, the OR for DM2 and IGT were 1.06 (95% CI 1.04-1.08) and 0.99 (95% CI 0.98-1.01), respectively. Conclusions The association between years of night work and diabetes is stronger among women than men. Longitudinal studies from ELSA-Brasil will be able to corroborate or refute these findings. [ABSTRACT FROM AUTHOR]

Objectives: This study investigates whether different shift work schedules, compared to day work, are associated with need for recovery (NFR), future disability, and retirement intentions for employees employed within different economic sectors over the course of their careers. Shift work exposure duration and the healthy worker effect are also examined. Methods: Data from the prospective Maastricht Cohort Study was used. Subsamples of industry (N=1877, all men) and healthcare (N=818, 624 women and 194 men) workers were separately investigated. GEE and Cox regression analyses were performed to investigate NFR longitudinally. Future disability was investigated using Cox regression, and retirement intentions were investigated using logistic regression analysis. Results: Compared to industry day workers, 3-shift industry workers were at risk of becoming a case of elevated NFR during follow-up; 3- and 5-shift industry workers were at risk for future disability. In healthcare, irregular shift work was a risk factor for disability among older shift workers. No significant results were found regarding retirement intentions. Findings were probably an underestimation as exposure duration to shift work and the healthy worker effect affected the results. Conclusions: Shift work was associated with higher levels of NFR and a higher risk of disability. However, shift work is a multifaceted concept as different types of shift work schedules are differently associated with these outcomes. Different shift work types exist and shift work schedules allow for optimization, indicating that measures to prevent adverse outcomes should be tailored for different types of shift work and over the course of the work career. [ABSTRACT FROM AUTHOR]