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Abstract: The objective was to examine the day-to-day variation in cortisol among healthy individuals and its relation to the time of saliva sampling, work, stress and fatigue. During 4 consecutive weeks, 14 office workers provided saliva samples (at awakening, 15min after awakening and at bedtime) and made diary ratings for each day. Results showed a variation in cortisol values between participants but also within individuals. After controlling for the individual differences, results showed that low cortisol levels in the morning were associated with sleepiness at awakening and anxiety, exhaustion, and poor health the day before. High evening levels of cortisol were associated with symptoms of stress and poor self-rated health. Further analysis of the cortisol awakening response (CAR) showed that all participants had a mixture of both a positive and negative responses. During mornings with a negative response participants stayed in bed for a longer time after the initial awakening, which might be a sign of snoozing, thus missing the awakening response. [Copyright &y& Elsevier]

Abstract: Stress is assumed to impair sleep, but there is very little empirical evidence for this using sleep recordings. Here, we recorded sleep (at home) in 33 normal participants on three nights, which followed days with low, high and intermediate stress. The participants made daily ratings of the level of stress/worries at bedtime and also two-hourly ratings of stress. Only those 16 individuals who differed in stress/worries between two nights were analysed. There was a significantly lower sleep efficiency (81.0% versus 85.2%) a higher percent Wake (22.6% versus 15.6%) and a longer latency to Stage 3 (33.9 versus 18.3min) during the nights with a higher stress/worry bedtime rating. None of the other sleep variables were affected. Also mean daytime stress ratings were significantly higher on the day preceding and following the high stress/worries sleep. It was concluded that moderate increases in stress/worries at bedtime are associated with moderately impaired sleep. [Copyright &y& Elsevier]

Stress is probably the most frequent cause of short-term insomnia, although it has seldom been documented polysomnographically. A few studies have shown that apprehension is associated with a reduction of slow wave sleep (SWS). The aim of the present study was to examine whether apprehension of the next working day would be related to sleep polysomnography and subjective sleep quality. In this analysis we made use of two different studies (n=37, mean age: 37 years) that provided inter-individual variation in apprehension of the subsequent working day. The results confirm previous findings that apprehension of a difficult next day is associated with decreased amount of SWS, increased percentage of stage 2 sleep, bedtime state anxiety and subjectively poor sleep. It is concluded that moderate “everyday” stress may disturb physiological restoration as indicated by the reduction of SWS. [Copyright &y& Elsevier]

Objective: In this longitudinal two-wave study, bidirectional relations between work-related stress and sleep quality were examined. Moreover, it was investigated whether perseverative cognition is a potential underlying mechanism in this association, related to both work-related stress and sleep quality.Methods: A randomly selected sample of Dutch employees received an online survey in 2012 and 2013. Of all invited employees, 877 participated in both waves. Structural equation modeling was performed to analyze the data.Results: We found evidence for reversed relations between work-related stress and sleep quality. Specifically, when controlling for perseverative cognition, work-related stress was not directly related to subsequent sleep quality, but low sleep quality was associated with an increase in work-related stress over time. Moreover, negative bidirectional associations over time were found between perseverative cognition and sleep quality, and positive bidirectional associations were found between work-related stress and perseverative cognition. Lastly, a mediation analysis showed that perseverative cognition fully mediated the relationship between work-related stress and sleep quality.Conclusion: The study findings suggest that perseverative cognition could be an important underlying mechanism in the association between work-related stress and sleep quality. The bidirectionality of the studied relationships could be an indication of a vicious cycle, in which work-related stress, perseverative cognition, and sleep quality mutually influence each other over time. [ABSTRACT FROM AUTHOR]

Abstract: Objective: Fatigue is related to a number of serious diseases, as well as to general well-being. It is also a major cause of sickness absence and use of health facilities. Still, the determinants of variations in fatigue are little investigated. The purpose of present study was to investigate the relationships between the daily variations of fatigue with sleep during the previous night, stress or disease symptoms during the same day — across 42 consecutive days of normal life. Methods: 50 individuals participated and gave diary reports and used an actigraph across the 42days. The data was analyzed using a multilevel approach with mixed model regression. Results: The analyses showed that the day-to-day variation in fatigue was related to (poor) sleep quality (p<.001) and (reduced) sleep duration (p<.01) the previous night, as well as to higher stress (p<.05), and to the occurrence of a cold or fever (p<.001) during the same day as the fatigue rating. Fatigue was also strongly related to poorer subjective health (p<.001) and sleepiness (p<.001) during the same day. Conclusion: The results indicate that prior sleep (and sleepiness) as well as stress and illness are consistently connected to how fatigue is experienced during normal living conditions. [Copyright &y& Elsevier]

Abstract: Background/objectives: The connection between stress and sleep is well established in cross-sectional questionnaire studies and in a few prospective studies. Here, the intention was to study the link between stress and sleep on a day-to-day basis across 42days. Methods: Fifty participants kept a sleep/wake diary across 42days and responded to daily questions on sleep and stress. The results were analyzed with a mixed model approach using stress during the prior day to predict morning ratings of sleep quality. Results: The results showed that bedtime stress and worries were the main predictors of sleep quality, but that, also, late awakening, short prior sleep, high quality of prior sleep, and good health the prior day predicted higher sleep quality. Conclusions: Stress during the day predicts subsequent sleep quality on a day-to-day basis across 42 days. The observed range of variation in stress/worries was modest, which is why it is suggested that the present data underestimates the impact of stress on subsequent sleep quality. [Copyright &y& Elsevier]

Abstract: Study objective: Stress as a cause of disturbed sleep is often taken for granted, but the longitudinal evidence is limited. The aim of this study was to evaluate new cases of poor sleep as a function of changes in reported work demands, work control, and work preoccupation. Methods: Longitudinal study of change with measures occurring twice within a 5-year interval during a period when the prevalence of impaired sleep was increasing in Sweden. The sample of companies was taken from northern Sweden (Norrland) and included 3637 individuals from the “WOLF Norrland” longitudinal cohort, collected through company health services. Measurement and results: During the measurement period, 16% of those studied developed new cases of impaired sleep. Logistic regressions adjusted for demographics, work environment factors, and disturbed sleep at T1 period one showed a significant increase in new cases for high work demands and high work preoccupation (OR=1.37; Ci=1.09–1.72 and OR=1.80; CI=1.42–2.28, respectively). The analysis of change in the predictors showed effects of a change from low to high work demands (OR=1.39; Ci=1.00–1.95) on new cases of impaired sleep. Consistent high work demands (high at both points) showed a similar increase (OR=1.49; Ci=1.06–2.11) but no effect was seen for reduced demands. Change in work preoccupation yielded stronger effects with OR=2.47 (1.78–2.47) for increased work preoccupation and OR=3.79 (2.70–5.31) for consistent high work preoccupation. Also, a reduction in work preoccupation was associated with a reduction in new cases of disturbed sleep. Control at work was not related to sleep. Stratification with respect to gender mainly led to fewer significant results (particularly for women) due to larger confidence intervals. Conclusions: It was concluded that self-reported work preoccupation predicts subsequent impairment of sleep and that increased preoccupation is associated with new cases of impaired sleep. Similar, but weaker, results were obtained for work demands. [Copyright &y& Elsevier]