Association of job strain with accelerometer-based sleep duration and timing of sleep among older employees.

Job strain has been associated with poor sleep quality and could lead to changes in duration and timing of sleep as well. This study examined the association of job strain with sleep duration, bedtimes and awakening times among public sector employees close to their retirement age. Differences in these sleep parameters between workdays and free days across job strain groups were examined. Duration and timing of sleep were measured repeatedly with accelerometers among 466 public sector employees in Finland (mean age 63 years, 86% women), who contributed to 759 measurements in total. Job demands (low/high) and control (low/high) measured by self-reports and job exposure matrix were used to identify low strain (low demand, high control), passive (low, low), active (high, high) and high strain (high, low) jobs. No differences in sleep duration were observed on workdays, whereas on free days those in the high strain group had longer sleep duration than those in the low strain and passive job groups. The high strain group also extended their sleep from workdays to free days more, the extension being on average 59 min (95% CI 42 min-75 min) when adjusted for several sociodemographic, work and health factors. This extension of sleep duration resulted mostly from a greater delay of awakening times from workdays to free days. Psychosocial work factors, such as job strain, need to be considered when promoting sufficient sleep duration among older employees, as those with job strain may have a greater need for recovery and sleep.

Associations of Sleep and Health Functioning with Premature Exit from Work: A Cohort Study with a Methodological Emphasis.

Sleep and functioning are associated with a risk of early workforce exit. However, patterns of change in sleep and functioning through time have not been investigated using person-oriented approaches to show what features of sleep and functioning are associated with an early exit. We examined the pattern of interactions between sleep and health functioning characterizing homogenous subgroups of employees and their associations with premature work exit. An additional aim was to provide a tutorial providing detailed description on how to apply these models, compared to traditional variable based risk factors. We analyzed data from 5148 midlife employees of the City of Helsinki, Finland, surveyed over three phases (2000-02, 2007, and 2012). Using repeated measures latent class analyses (RMLCA) we classified people into groups based on their trajectories in sleep and functioning. We identified four longitudinal groups: (1) Stable good sleep and functioning (reference), (2) Persistent sleep problems and good or moderate functioning, (3) Poor functioning with good sleep, and (4) Problematic sleep and health functioning. Compared to group 1, elevated risk was found in all classes with group 4 being the worst. In conclusion, focusing on person-orientated patterns of interactions between sleep and functioning helped produce qualitatively different and quantitatively stronger predictions than using conventional risk factor methodology. Thus, longitudinal person-oriented approaches may be a more powerful method for quantifying the role of sleep and health functioning as risks for premature exit from work.

Changes in accelerometer-measured sleep during the transition to retirement: the Finnish Retirement and Aging (FIREA) study.

STUDY OBJECTIVES: Retirement is associated with increases in self-reported sleep duration and reductions in sleep difficulties, but these findings need to be confirmed by using more objective measurement tools. This study aimed at examining accelerometer-based sleep before and after retirement and at identifying trajectories of sleep duration around retirement. METHODS: The study population consisted of 420 participants of the Finnish Retirement and Aging study. Participants' sleep timing, sleep duration, time in bed, and sleep efficiency were measured annually using a wrist-worn triaxial ActiGraph accelerometer on average 3.4 times around retirement. In the analyses, sleep on nights before working days and on nights before days off prior to retirement were separately examined in relation to nights after retirement. RESULTS: Both in bed and out bed times were delayed after retirement compared with nights before working days. Sleep duration increased on average by 41 min (95% confidence interval [CI] = 35 to 46 min) from nights before working days and decreased by 13 min (95% CI = -20 to -6 min) from nights before days off compared with nights after retirement. By using latent trajectory analysis, three trajectories of sleep duration around retirement were identified: (1) shorter mid-range sleep duration with increase at retirement, (2) longer mid-range sleep duration with increase at retirement, and (3) constantly short sleep duration. CONCLUSIONS: Accelerometer measurements support previous findings of increased sleep duration after retirement. After retirement, especially out bed times are delayed, thus, closely resembling sleep on pre-retirement nights before non-working days.

Work participation trajectories among 1,098,748 Finns: reasons for premature labour market exit and the incidence of sickness absence due to mental disorders and musculoskeletal diseases.

BACKGROUND: Early exit from paid employment is a notable public health and societal challenge. Previous research has largely focused on the relationships among variables instead of the relationships among individuals with different work participation history. Person-oriented methods enable to identify latent groups of individuals who are likely to follow similar development in their work participation over time. We thus aimed to identify work participation trajectories during early and midlife careers and their social determinants using large nationally representative data comprising over 1 million initially employed individuals and a 10-year follow-up for their work participation. A further aim was to determine the cumulative incidence of sickness absence due to key diagnostic groups, mental disorders and musculoskeletal diseases within the trajectories. METHODS: Young (25-38 years at baseline, n = 495,663) and midlife (39-52 years at baseline, n = 603,085) Finnish people, all working in 2004, were followed up through 2013, with registers of the Social Insurance Institution, and the Statistics Finland. The registers provided data for work participation and its determinants, as well as for computing the cumulative incidence of sickness absence. Latent class growth analysis was used to identify trajectories. RESULTS: Three distinctive trajectories were identified: temporary exit, permanent exit, and continuously employed people. As compared to the other trajectories, those belonging to the permanent exit trajectory were more likely men, manual workers and had a lower income. The cumulative incidence of sickness absence due to mental disorders was highest in the permanent exit trajectory group. For musculoskeletal diseases, the cumulative incidence of sickness absence increased in the permanent exit trajectory mainly in the older age groups. CONCLUSION: Distinct group-based trajectories of early work exit can be identified in a representative cohort of initially employed people. Focusing on the determinants of premature exit and early intervention to tackle increasing sickness absence may promote work participation particularly in the most vulnerable groups.

Does removal of work stress explain improved sleep following retirement? The Finnish Retirement and Aging study.

STUDY OBJECTIVES: Relief from work stress has been hypothesized to explain improvements in sleep duration and quality following retirement, but this has not been confirmed with longitudinal studies. By using repeat sleep data, we examined the role of removal of work-related stressors in changes in sleep at retirement. METHODS: The study population consisted of 2,053 participants from the Finnish Retirement and Aging study. Participants' sleep duration, sleep difficulties (difficulties falling asleep, difficulties maintaining sleep, waking up too early in the morning, nonrestorative sleep), daytime tiredness, and sleep loss due to worry were assessed using surveys conducted once a year before and after retirement (average number of repeat surveys 3.5 [range 2-5] per participant). We used Poisson regression with generalized estimating equations to examine the associations between work-related stressors (job strain, low work time control, effort-reward imbalance, and organizational injustice) and changes in sleep at retirement. RESULTS: An increase in sleep duration and decrease in waking up too early in the morning, nonrestorative sleep, daytime tiredness, and sleep loss due to worry were observed shortly after retirement. No systematic associations across the work-related stressors and changes in sleep characteristics were observed. Higher number of work-related stressors before retirement was not associated with a greater magnitude of favorable changes in any of the postretirement sleep characteristics investigated. CONCLUSIONS: This longitudinal study suggests that perceived sleep improves shortly after retirement and that these changes are mainly driven by factors other than relief from work stress.

Trajectories in hypnotic use and approaching death: a register linked case-control study.

PURPOSE: Whether the association between hypnotic and increased mortality risk is created by causation or confounding, has been long debated. We further examined the possibility of confounding by indication with a comprehensive approach. METHODS: The National FINRISK Study cohorts of 1997, 2002, and 2007 (25,436 participants aged 25-74) were followed up until July 2012. There were 1822 deaths, and at least one gender, baseline age and cohort matched 'control' was found for 1728 'cases' yielding a final analytical sample of 3955 individuals. An index age, equivalent to the age at death of their respective cases' was set for each control. Hypnotic drug purchases were followed from the Finnish nationwide register during a 36-month run-up period before the date of death/index date. The prevalence and incidence of hypnotic purchases were compared between cases and matched controls. Moreover, latent developmental trajectories of purchases were modelled and their relations with specific and all-cause death risks were analysed. RESULTS: An increasing difference between cases and controls was observed as regards the use of hypnotic drugs. During the last 30 months before the date of death/index date, the rate ratio of incident purchases between cases and controls was 2.37 (95% CL, 1.79-3.12) among older and 3.61 (95% CL, 2.37-5.89) among younger individuals. The developmental trajectories of hypnotic drug purchases were differently and by interpretation plausibly associated with specific mortality risks. CONCLUSIONS: In most cases the association between hypnotics and mortality risk is created by symptomatic treatment when death is approaching.

Rethinking the sleep-health link.

Sleep is important for the physical, social and mental well-being of both children and adults. In this paper, we discuss the need to consider sleep as a multidimensional construct and as a component of total 24-hour activity. First, we make a case for considering sleep as a multidimensional construct, whereby all characteristics of sleep (including duration, quality, timing, and variability) and their links with health are examined. Second, we argue that sleep should also be conceptualized as part of the daily spectrum of time-use, along with other types of activity. We propose novel statistical models, in particular compositional data analysis (CoDA), as appropriate analytical methods for a new sleep paradigm.

Association of sleep duration and sleep quality with the physical, social, and emotional functioning among Australian adults.

OBJECTIVES: We aimed to evaluate the interaction of two key determinants of sleep health, quantity and quality, with physical, emotional, and social functioning, in the general population. DESIGN: Nationally-representative Australian cross-sectional study. SETTING: General population. PARTICIPANTS: 14,571 people aged 15 or older in Household, Income and Labor Dynamics in Australia (HILDA) in 2013. MEASUREMENTS: The associations of sleep quality (good/poor) in combination with mid-range (6-8 hours), short (<6) or long (>8) sleep duration with functioning, determined from the SF-36, were evaluated using logistic regression adjusting for sociodemographic, relationships, health behaviors, obesity, pain, and mental and physical illness confounders. RESULTS: After adjusting for gender, and age, poor sleep quality in combination with short, mid-range and long sleep was associated with worse physical, emotional and social functioning. Pain and comorbid illness explained much of these associations, while attenuation from other covariates was minor. The associations of poor sleep quality with worse functioning remained after full adjustment regardless of sleep duration, while among people with good quality sleep, only those with long sleep duration reported poorer functioning. CONCLUSIONS: Poor sleep quality has robust associations with worse functioning regardless of total duration in the general population. There appears to be a substantial number of functional short sleepers with good quality sleep.

Changes in Sleep Difficulties During the Transition to Statutory Retirement.

Study Objectives: This study examined changes in sleep during the transition from full-time work to statutory retirement. Both the prevalence of any sleep difficulty and the prevalence of specific sleep difficulties, such as difficulties falling asleep, difficulties maintaining sleep, waking up too early in the morning, and nonrestorative sleep, were examined. Methods: Data from the Finnish Public Sector study were used. The study population consisted of 5,807 Finnish public sector employees who retired on statutory basis between 2000 and 2011. The participants responded on the Jenkins Sleep Problem Scale Questionnaire before and after retirement in surveys conducted every 4 years. Results: At the last study wave before retirement, 30% of the participants had sleep difficulties. Prevalence of any sleep difficulty decreased during the retirement transition: the risk ratio (RR) for having sleep difficulties in the first study wave following retirement compared with the last study wave preceding retirement was 0.89 (95% confidence interval [CI] 0.85-0.94). During the retirement transition, both waking up too early in the morning (RR = 0.76, 95% CI 0.69-0.82) and nonrestorative sleep (RR = 0.47, 95% CI 0.42-0.53) decreased, whereas there was no change in difficulties falling asleep or difficulties maintaining sleep. The decreases in sleep difficulties occurred primarily among those with psychological distress, suboptimal self-rated health, short sleep duration, and job strain before retirement. Conclusions: These longitudinal data suggest that transition to statutory retirement is associated with a decrease in sleep difficulties, especially waking up too early in the morning and nonrestorative sleep.

Past, present, and future: trends in sleep duration and implications for public health.

Sleep is important for the physical, social and mental well-being of both children and adults. Over the years, there has been a general presumption that sleep will inevitably decline with the increase in technology and a busy 24-hour modern lifestyle. This narrative review discusses the empirical evidence for secular trends in sleep duration and the implications of these trends.

Changes in Sleep Duration During Transition to Statutory Retirement: A Longitudinal Cohort Study.

Study Objectives: This study examined whether sleep duration changes during the transition from full-time work to statutory retirement and, if this were the case, which preretirement factors, including sociodemographic, work, lifestyle, and health factors, predict these changes. Methods: Data from repeated surveys of the Finnish Public Sector study, linked to records of retirement, were used. The study population consisted of 5785 participants who retired on a statutory basis in 2000-2011 and who had responded to surveys on sleep duration at least once immediately before and after their retirement (mean number of repeat study waves 3.6). Linear regression analyses with generalized estimating equations were used to examine changes in sleep duration around retirement. Results: Before retirement there was a slight decrease in sleep duration. During the 4-year retirement transition, sleep duration increased from 7 hours 0 minutes (95% confidence interval [CI] 6 hours 54 minutes to 7 hours 6 minutes) to 7 hours and 22 minutes (95% CI 7 hours 16 minutes to 7 hours 27 minutes); thus, mean increase being 22 minutes. Increase in sleep duration was greatest in those who were short sleepers, heavy drinkers, or had sleep difficulties. After the retirement transition, sleep duration remained at approximately the same level, as no significant changes were observed. Conclusions: This longitudinal study suggests that transition from full-time work to statutory retirement is associated with an increase in sleep duration.

Nightmares as predictors of suicide: an extension study including war veterans.

Nightmares are intensive dreams with negative emotional tone. Frequent nightmares can pose a serious clinical problem and in 2001, Tanskanen et al. found that nightmares increase the risk of suicide. However, the dataset used by these authors included war veterans in whom nightmare frequency - and possibly also suicide risk - is elevated. Therefore, re-examination of the association between nightmares and suicide in these data is warranted. We investigated the relationship between nightmares and suicide both in the general population and war veterans in Finnish National FINRISK Study from the years 1972 to 2012, a dataset overlapping with the one used in the study by Tanskanen et al. Our data comprise 71,068 participants of whom 3139 are war veterans. Participants were followed from their survey participation until the end of 2014 or death. Suicides (N = 398) were identified from the National Causes of Death Register. Frequent nightmares increase the risk of suicide: The result of Tanskanen et al. holds even when war experiences are controlled for. Actually nightmares are not significantly associated with suicides among war veterans. These results support the role of nightmares as an independent risk factor for suicide instead of just being proxy for history of traumatic experiences.

Chronotype differences in timing of energy and macronutrient intakes: A population-based study in adults.

OBJECTIVE: To examine the association between chronotype and timing of energy and macronutrient intakes in adults. METHODS: The study sample included 1,854 participants from the National FINRISK 2007 and FINDIET 2007 studies, aged 25 to 74 years. Diet was assessed with 48-hour dietary recalls. Chronotype was assessed with a shortened version of Horne and Östberg's Morningness-eveningness Questionnaire. Associations between chronotype and intakes of energy and macronutrients in the morning (by 10 am) and in the evening (after 8 pm) were analyzed with linear regression and ANOVA followed by Bonferroni post hoc test. RESULTS: In the morning, evening types had lower energy and macronutrient intakes (except for sucrose of which they had a higher intake) than morning types (P < 0.05), while in the evening, evening types had higher intakes of energy, sucrose, fat, and saturated fatty acids than morning types (P < 0.05). On the weekend, chronotype differences in evening intakes of energy, sucrose, and fat intake were more pronounced, and evening types had more eating occasions and more irregular meal times than morning types. CONCLUSIONS: Postponed energy and macronutrient intake timing of evening types with unfavorable dietary patterns may put them at higher risk of obesity and metabolic disturbances in the future.

Gender differences in actual and preferred nocturnal sleep duration among Finnish employed population.

OBJECTIVE: Sufficient sleep is essential for health and working capacity. Shorter sleep duration on workdays is often compensated by sleeping longer during leisure days. Gender dissimilarities in sleep quality are acknowledged. Our aim was to study the less known gender differences in sleep duration. METHODS: A population based study with a total of 1049 middle-aged regularly working women (n=524) and men (n=525). A questionnaire of sleep durations on workdays and leisure days, preferred sleep duration, with health-related quality of life and health behavior. RESULTS: Women slept 14min longer on workdays (p<0.002) and 27min longer on leisure days (p<0.002) and had 32min longer preferred sleep duration (p<0.001) than men. Compared to workdays, women slept 1h 57minutes longer and men 1h 42min longer on leisure days (gender p<0.001). On workdays, both women and men slept less than their preferred sleep duration and again, with more extensive difference in women (gender-interaction p<0.001). On leisure days the excessive sleep time did not differ between genders (p=0.346). None of the explanatory variables explained the gender differences in sleep durations. CONCLUSIONS: Sleep loss on workdays is presumably more pronounced in women, since despite their longer sleep on workdays, the gender differences persist in both sleep duration on leisure days and in preferred sleep duration.

The associations between chronotype, a healthy diet and obesity.

Unhealthy diet has been associated with obesity. Evening type has been associated with unhealthier food and nutrient intake that could predict a higher risk of obesity among them as compared to morning type. However, thus far no study has examined the interrelationships between chronotype, a healthy diet and obesity. We examined whether a healthy diet mediates the association between chronotype and obesity and whether chronotype modifies the association between a healthy and obesity. The National FINRISK 2007 Study included 4421 subjects aged 25-74 years. Diet was assessed using a validated food frequency questionnaire. Baltic Sea diet score (BSDS), including nine dietary components, was used as a measure of adherence to a healthy Nordic diet. Weight, height, body fat percentage and waist circumference were measured, and body mass index values were calculated. Chronotype was assessed using a shortened version of Horne and Östberg's morningness-eveningness questionnaire (MEQ). The sum score calculated from MEQ was either used as a continuous variable or divided into tertiles of which the lowest tertile demonstrated evening preference and the highest tertile demonstrated morning preference. A series of regression analyses were conducted to determine whether the BSDS mediates the association between chronotype and obesity. Likelihood ratio test was used to determine whether chronotype modifies the association between the BSDS and the obesity measures. After testing the interaction, chronotype-stratified analysis for the association between the BSDS and obesity measures was determined by linear regression. Generally, the evening types had lower adherence to the BSDS and were more often smokers (men), physically inactive and had lower perceived health than the other chronotypes (p < 0.05). The poorer health behavior of this group, however, was not manifested in their obesity measures, and no evidence that the BSDS would mediate the association between chronotype and obesity was found (p > 0.05). No evidence that chronotype would modify the association between the BSDS and obesity was found either (p > 0.05).

Winter is coming: nightmares and sleep problems during seasonal affective disorder.

Sleep problems, especially nightmares and insomnia, often accompany depression. This study investigated how nightmares, symptoms of insomnia, chronotype and sleep duration associate with seasonal affective disorder, a special form of depression. Additionally, it was noted how latitude, a proxy for photoperiod, and characteristics of the place of residence affect the prevalence of seasonal affective disorder and sleep problems. To study these questions, data from FINRISK 2012 study were used. FINRISK 2012 consists of a random population sample of Finnish adults aged 25-74 years (n = 4905) collected during winter from Finnish urban and rural areas spanning the latitudes of 60°N to 66°N. The Seasonal Pattern Assessment Questionnaire was used to assess symptoms of seasonal affective disorder. Participants with symptoms of seasonal affective disorder had significantly increased odds of experiencing frequent nightmares and symptoms of insomnia, and they were more often evening chronotypes. Associations between latitude, population size and urbanicity with seasonal affective disorder symptoms and sleep disturbances were generally not significant, although participants living in areas bordering urban centres had less sleep problems than participants from other regions. These data show that the prevalence of seasonal affective disorder was not affected by latitude.

Prolonged sleep restriction induces changes in pathways involved in cholesterol metabolism and inflammatory responses.

Sleep loss and insufficient sleep are risk factors for cardiometabolic diseases, but data on how insufficient sleep contributes to these diseases are scarce. These questions were addressed using two approaches: an experimental, partial sleep restriction study (14 cases and 7 control subjects) with objective verification of sleep amount, and two independent epidemiological cohorts (altogether 2739 individuals) with questions of sleep insufficiency. In both approaches, blood transcriptome and serum metabolome were analysed. Sleep loss decreased the expression of genes encoding cholesterol transporters and increased expression in pathways involved in inflammatory responses in both paradigms. Metabolomic analyses revealed lower circulating large HDL in the population cohorts among subjects reporting insufficient sleep, while circulating LDL decreased in the experimental sleep restriction study. These findings suggest that prolonged sleep deprivation modifies inflammatory and cholesterol pathways at the level of gene expression and serum lipoproteins, inducing changes toward potentially higher risk for cardiometabolic diseases.

Prevalence of insomnia-related symptoms continues to increase in the Finnish working-age population.

In 2008, we published epidemiological data from 1972 to 2005 that suggested an increase in insomnia-related symptoms among the working-age population. The results were based on the National FINRISK (FR) Study samples of the Finnish adult population aged 25-64, and on the Finnish Quality of Work Life Surveys (FQWLS), carried out among Finnish salary earners. Both of these ongoing studies have since provided two new estimates of insomnia-related symptoms. Chronic insomnia-related symptoms were 9.0% (95% CI 8.3-9.7), 9.6% (95% CI 8.8-10.4) in FR 2007 and 2012, respectively; and 9.1% (95% CI 8.3-10.0), 9.2% (95% CI 8.4-10.1) in FQWLS 2008 and 2013, respectively. Occasional insomnia-related symptoms were 45.3% (95% CI 44.1-46.6), 42.5% (95% CI 41.1-43.9) in FR 2007 and 2012, respectively; and 40.3% (95% CI 38.8-41.7), 44.8% (95% CI 41.1-43.9) in FQWLS 2008 and 2013, respectively. The new estimates further strengthen the interpretation of the ongoing increase in occasional insomnia-related symptoms among the Finnish general adult population. The increase in occasional symptoms was most prominent among employees. However, chronic insomnia symptoms showed no further increase.