Association of sickness absence with poor sleep and depressive symptoms in shift workers

A cross-sectional study was conducted to evaluate the contribution of daily sleep habits and depressive symptoms to sickness absences of shift workers. A self-administered questionnaire that solicited answers about sleep, symptoms of depression, sickness absence, diseases/injuries, and lifestyle factors was submitted to a sample of 522 rotating shift workers between the ages of 18-59 (mean 27) yrs of an electric equipment manufacturing company. The seven features of sleep queried were daily hours of sleep, time to fall asleep, awakening during sleep, early morning awakening, sleep well at night, sufficiency of sleep, and excessive daytime sleepiness at work. The responses were assessed over the subject's previous 1-yr period. Each sleep feature, except daily sleeping hours, was dichotomized by the following responses: (1) taking more than 30min to fall asleep (difficulty initiating sleep; DIS), (2) awakening during sleep almost every day (difficulty maintaining sleep; DMS), (3) early morning awakening almost every day (EMA), (4) sleeping very poorly or not so well at night, (5) definite or somewhat insufficient nightly sleep, and (6) excessive daytime sleepiness at work almost every day (EDS). Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression (CES-D) scale. Sickness absence was calculated by asking subjects "How many days in total have you been absent from work due to sickness, including paid vacation, in the last 1-yr period?" The responses were divided into three groups that included no (0 days) sickness absences (reference group, n=235 subjects), 1 to 4 days (short-term, n=199 subjects), and 5 days or more (long-term, n = 88 subjects). Compared to the prevalence of sleep features of the reference group, workers with short-term absence showed a significantly higher prevalence of EMA with an odds ratio (OR) of 5.3, 95% confidence interval (CI) 1.3-22.0. Long-term absence was significantly associated with DMS (OR = 2.1, 95%CI 1.0-4.6), EMA (OR = 5.6, 95%CI 1.0-28.7), sleeping poorly at night (OR= 2.6, 95%CI 1.4-5.0), and high depressive symptoms (OR = 2.0, 95%CI 1.0-3.7) according to the CES-D score of >16, after adjusting for multiple confounding variables. These data point to an association between both the parameters of poor sleep and symptoms of deep depression when self-reported sickness absence is frequent. The association is particularly strong with long-term absence in male shift workers.     

Correlations between sleep patterns and cardiovascular diseases in a Chinese middle-aged population

Epidemiological and animal studies have suggested an association between habitual sleep patterns and cardiovascular (CV) disease, but the results are still controversial. Therefore, the aims of this study are to investigate the relationships between habitual sleep patterns and CV disease based on Prospective Urban Rural Epidemiology (PURE) China study. PURE China study recruited 46 285 participants, aged 35–70, from 12 provinces and 115 communities in China. Habitual sleep patterns and CV disease were self-reported. Multilevel logistic regression was used in our analysis. In this study, 39 515 participants were eligible in our analysis, including 23 345 (59.1%) women and 16 170 (40.9%) men. Sleeping ≥9 h per day was associated with increased odds of CV disease (OR = 1.16, 95% CI: 1.01–1.32, p = 0.033) compared with sleeping 7–8 h per day. Taking daytime naps was also associated with an increased odds of CV disease, and the CV odds increased with increasing napping duration (p for trend < 0.001). For the sleeping < 6 h per day, we only found an association with coronary artery disease (CAD) (OR = 1.58, 95% CI: 1.01–2.48, p = 0.046). Participants with only 7–8 h sleep per night had lowest prevalence of CV disease (OR = 0.77, 95% CI: 0.65–0.90, p = 0.001) compared with other sleep patterns. Napping, long and short duration of habitual sleep may increase the odds of CV disease. Only participants sleeping 7–8 hours at night are recommended in this study, and large longitudinal studies are needed to confirm these results.     

Association between depressive symptoms and morningness-eveningness,sleep duration and rotating shift work in Japanese nurses

Higher depressive symptoms have been reported in rotating shift workers compared with day workers. Depressive symptoms in adults who do not engage in night work have also been shown to be associated with chronotype and sleep duration. This study examines associations between depressive symptoms, morningness-eveningness (i.e. the degree to which people prefer to be active in the morning or the evening), sleep duration and rotating shift work. Japanese nurses (1252 day workers and 1780 rotating shift workers, aged 20–59) were studied using a self-administered questionnaire. The questionnaire covered depressive symptoms, morningness-eveningness, sleep habits and demographic characteristics of the participants. The Center for Epidemiologic Studies Depression Scale (CES-D) was used to determine the levels of depressive symptoms. A Japanese version of the Morningness-Eveningness Questionnaire (MEQ) was used to measure morningness-eveningness. The CES-D score of shift workers was significantly (p < 0.05) higher than that of day workers. The MEQ score was significantly (p < 0.05) lower (i.e. greater eveningness) in shift workers than in day workers. Sleep duration on the day shift was significantly (p < 0.05) shorter in shift workers than in day workers. Simple linear regression revealed that the MEQ score, sleep duration on the day shift and current work shift (i.e. rotating shift work) were significantly (p < 0.05) associated with the CES-D score. Multivariate linear regression indicated that greater eveningness and shorter sleep duration were independently associated with higher CES-D scores, while rotating shift work was not. These associations between the MEQ score, the sleep duration and the CES-D score were also confirmed in both day workers and shift workers when the groups were analyzed separately. These results suggest that greater eveningness and shorter sleep duration on the day shift were independently associated with higher levels of depressive symptoms, which may explain associations between rotating shift workers and depressive symptoms. These findings have important implications for the development of novel strategies for preventing poor mental health in day workers and rotating shift workers.     

Sleep Parameters among Offshore Workers: An Initial Assessment in the Campos Basin,Rio De Janeiro,Brazil

Shift work has potentially adverse effects on health, particularly on sleep. The purpose of the present study was to assess sleep parameters among personnel working in oil and gas offshore installations in the Campos Basin, Rio de Janeiro, Brazil. One hundred and seventy-nine subjects were asked to complete a sleep questionnaire with multiple-choice answers. Offshore workers were divided into two groups according to their work schedule: (1) fixed daytime workers (n = 86; age: 35.8 ± 9.6 yrs) and (2) shift (n = 87) or night (n = 6) workers (total n = 93; age: 37.7 ± 9.7 yrs). Shift/night workers reported poor sleep more frequently than the daytime workers (20.4% vs. 1.2%, p < 0.01), as well as habitual difficulty in falling asleep (15.1% vs. 4.7%, p < 0.01), long latency of sleep onset (28% vs. 7%, p < 0.01), fragmented sleep (45.2% vs. 16.3%, p < 0.01), short sleep episodes (44.1% vs. 16.3%, p < 0.01), irregular bedtimes (29.0% vs. 12.8%, p < 0.01), and feeling tired upon awakening (15.1% vs. 3.5%, p < 0.01). Habitual napping and loud snoring were reported twice as often in shift/night than in day workers (p < 0.01). Nightmares, somnambulism, and unpleasant feeling in the legs were equality reported by both groups (p > 0.05). Few offshore workers had sought medical help for their sleep problems. A higher number of shift/night workers reported feelings of sadness compared with day workers (26.9% vs. 9.3%, p < 0.01). The findings of this study show that subjective reports of sleep-related problems are quite common among Brazilian offshore shift workers. Reliance on self-reported sleep problems and a cross-sectional design are the main limitations of our study.     

Evening chronotype is associated with poor cardiovascular health and adverse health behaviors in a diverse population of women

ABSTRACT

Chronotype reflects time of day preferences for performing daily activities. Previous research within Asian and European cohorts indicates evening chronotype is associated with elevated cardiometabolic risk. However, evidence is limited from population-based US cohorts, particularly among women in whom evening chronotype prevalence may become higher after middle-age, coinciding with life stages associated with higher cardiovascular disease (CVD) risk. This cross-sectional study evaluated associations of chronotype with overall cardiovascular health (CVH), health behaviors, and cardiometabolic risk factors among 506 women (mean age = 37 ± 16y, 62% racial/ethnic minority) in the American Heart Association (AHA)’s Go Red for Women Strategically-Focused Research Network cohort at Columbia University (New York City, NY, USA). Chronotype was assessed using the validated Morningness-Eveningness Questionnaire (MEQ) and categorized as “evening”, “intermediate”, and “morning” chronotypes. Health behaviors (diet, physical activity, and sleep) were assessed using validated questionnaires. Anthropometrics, clinical blood pressure, and blood biomarkers were assessed at the clinic visit. CVH was evaluated using the AHA Life’s Simple 7 (LS7) metrics; LS7 scores of 0–8 and 9–14 were considered indicative of poor and moderate-to-high CVH, respectively. Linear and logistic regression models adjusted for age, race/ethnicity, education, health insurance, and menopausal status were used to examine associations of MEQ scores and chronotype categories with overall CVH, clinical cardiometabolic risk factors, and health behaviors. Overall, 13% of women identified as evening chronotypes, while 55% and 32% reported being intermediate and morning types. In linear models, higher MEQ scores were associated with higher AHA LS7 scores (β(SE) = 0.02(0.01); p = .014), indicative of more favorable CVH, and with health behaviors not included in the LS7. Higher MEQ scores were also associated with lower Pittsburgh Sleep Quality Index, i.e. better sleep quality, (β(SE) = ?0.07(0.02), p < .0001), lower insomnia severity (β(SE) = ?0.14(0.01), p < .0001), shorter time to fall asleep (β(SE) = ?0.28(0.14), p = .044), and less sedentary time (β(SE) = ?0.11(0.03), p = .001). In logistic regression models, evening chronotype, compared to intermediate/morning type, was associated with higher odds of having poor CVH (OR(95%CI):2.41(1.20–4.85)), not meeting AHA diet (OR(95%CI):2.89(1.59–5.23)) and physical activity guidelines (OR(95%CI):1.78(1.03–3.07)), and having short sleep (OR(95%CI):2.15(1.24–3.73)) or insomnia (OR(95%CI):2.69(1.53–4.75)). The evening type compared to morning type was also associated with being a current smoker (OR(95%CI):2.14(1.02–4.52)) and having poor sleep quality (OR(95%CI:2.35(1.27–4.37)) and long sleep onset latency (OR(95%CI:1.89(1.00–3.56)). In our cohort of women, evening chronotype was related to poor CVH, likely driven by its influence on health behaviors. These findings, although warranting confirmation prospectively in other populations, suggest chronotype is an important factor to consider and possibly target when designing lifestyle interventions for CVD prevention.     

EVENING PREFERENCE IS RELATED TO THE INCIDENCE OF DEPRESSIVE STATES INDEPENDENT OF SLEEP-WAKE CONDITIONS

Although evening preference has recently been identified as a risk factor for depression, it has not been substantiated whether evening preference is a direct risk factor for depressive states, or if it is associated secondarily through other factors, such as delayed sleep timing and shortened sleep duration. The objective of this study is to investigate associations in Japanese adult subjects between evening preference and incidence of depressive states, adjusting for various sleep parameters related to depressive states. The Morningness-Eveningness Questionnaire (MEQ), the Pittsburgh Sleep Quality Index (PSQI), and the Center for Epidemiologic Studies Depression Scale (CES-D) were administered to 1170 individuals (493 males/677 females; mean and range 38.5 and 20–59 yrs) to assess their diurnal preferences, sleeping states, and presence of depression symptoms. Subjects were classified into five chronotypes based on MEQ scores. Evening preference was associated with delayed sleep timing, shortened sleep duration, deteriorated subjective sleep quality, and worsened daytime sleepiness. Logistic regression analysis demonstrated that the extreme evening type (odds ratio [OR]?=?1.926, p?=?.018) was associated with increased incidence of depressive states and that the extreme morning type (OR?=?0.342, p?=?.038) was associated with the decreased incidence of depressive states, independent of sleep parameters, such as nocturnal awakening (OR?=?1.844, p?<?.001), subjective sleep quality (OR?=?2.471, p?<?.001), and daytime sleepiness (OR?=?1.895, p?=?.001). However, no significant associations were observed between the incidence of depressive states and sleep duration, sleep timing, and sleep debt (levels of insufficient sleep). Although the findings of this study do not demonstrate a causative relationship between evening preference and depression, they do suggest the presence of functional associations between mood adjustment and biological clock systems that regulate diurnal preference. They also suggest that evening preference might increase susceptibility to the induction of mood disorders. (Author correspondence: mishima@ncnp.go.jp)     

Objective working hour characteristics and work–life conflict among hospital employees in the Finnish public sector study

This epidemiological cohort study, based on Finnish public sector data, investigated the associations between objective working hour characteristics and work–life conflict in day and shift work. The comprehensive data of hospital workers (n = 8 931, 92% women, average age 45 years), consisted of survey responses from 2012, linked with the payroll data of working hour characteristics from 91 days preceding the survey. Logistic regression analysis was used to investigate the associations between working hour characteristics and experiencing work–life conflict often/very often. The analyses were adjusted for age (< 39, 40–49 and >50 years), sex, level of education, marital status, number of small (0–6 years) and school-aged (7–18 years) children, and the overall stressfulness of the life situation. We also conducted stratified analyses of age and sex on the basis of significant interactions. Difficulties in combining work and life were more often associated with shift work without night shifts and shift work with night shifts than with day work (41% and 34 versus 27%; OR for shift work with night shifts 1.78, 95% CI 1.59–2.00, OR for shift work without night shifts 1.42, 95% CI 1.26–1.60). A high proportion (> 25%) of long (> 40h, (OR 1.26, 95% 1.14–1.39) and very long (> 48h, OR 1.31, 95% CI 1.15–1.49) weekly working hours were associated with work–life conflict, and in the stratified analysis, the latter was also true among women (OR 1.54, 95% CI 1.25–1.89). Of the unsocial working hour characteristics, a relatively large amount (> 10% of all shifts) of evening (OR 1.56, 95% CI 1.41–1.72) and night shifts (OR 1.46, 95%CI 1.32–1.61), a high proportion (> 25% of all shifts) of quick returns (< 11h) (OR 1.46, 95% CI 1.31–1.63), and weekend work (OR 1.44, 95% CI 1.31–1.58) were associated with work–life conflict. A large amount of single days off (> 25% of all days off) was associated with work–life conflict among men (OR 1.90, 95% CI 1.11–3.25), but not in the whole sample. When the two types of shift work were analyzed separately, shift work without night shifts and very long work weeks had higher odds (OR 1.47, 95% CI 1.20–1.80) of work–life conflict than shift work with night shifts. Conversely, weekend work and evening shifts had higher odds of work–life conflict among shift workers with night shifts (OR 1.74, 95% 1.55–1.96; (OR 1.57, 95% CI 1.40–1.77) than among those without night shifts. To conclude, this study shows that shift workers with and without night shifts more often have difficulties combining work and life than day workers. Several unsocial working hour characteristics, including long work weeks, evening and night shifts, weekend work, and quick returns, are associated with work–life conflict.     

Permanent night workers´ sleep and psychosocial factors in hospital work. A comparison to day and shift work

ABSTRACT

We aimed to study whether permanent night workers sleep and psychosocial factors differ from day workers and shift workers. The participants (n = 9 312, 92% females, average age 45 years, most commonly nurses and departmental secretaries) were day workers (DW, n = 2 672), shift workers (SW, n = 6 486) and permanent night workers (PNW, n = 154). The Finnish Public Sector survey responses from six hospital districts from 2012 were combined to payroll data from 91 days preceding the survey. The data were analyzed using Pearson χ²-test, one-way ANOVA and multinomial logistic regression analysis. The PNWs reported slightly longer average sleep length than the SWs or the DWs (7:27 vs. 7:13 and 7:10 h, p < 0.001). The PNWs reported least often difficulties in maintaining sleep (p < 0.001) compared to the SWs and the DWs. The PNWs reported most often difficulties to fall asleep and fatigue during free-time (p-values <0.001). The DWs and PNWs experienced less often work-life conflict than the SWs (25 and 26 vs. 38%, p < 0.001). The PNWs were more often satisfied with autonomy at work and appreciation and fair treatment by colleagues than the DWs or the SWs (p < 0.001). The SWs and PNWs reported remarkably higher occurrence of verbal (p < 0.001, OR 3.71, 95% CI 3.23–4.27 and OR 7.67, 95% CI 5.35–10.99, respectively) and physical workplace violence (p < 0.001, OR 9.24, 95% CI 7.17–11.90 and OR 28.34, 95% CI 16.64–43.06, respectively) compared to DWs. Conclusively, PNWs reported contradictory differences in sleep quality compared to DWs and SWs. PNWs are more often satisfied with their colleagues and autonomy at work than DWs or SWs but face workplace violence remarkably more often.     

Association between light exposure at night and manic symptoms in bipolar disorder: cross-sectional analysis of the APPLE cohort

ABSTRACT

Previous studies have found that keeping the room dark at night was associated with a decrease in manic symptoms for patients with bipolar disorder (BD). However, the association between light at night of real-life conditions and manic symptoms is unclear. We investigated the association between bedroom light exposure at night and manic symptoms in BD patients. One-hundred and eighty-four outpatients with BD participated in this cross-sectional study. The average light intensity at night during sleep was evaluated using a portable photometer for seven consecutive nights. Manic symptoms were assessed using the Young Mania Rating Scale (YMRS), and scores ≥5 were treated as a “hypomanic state.” The median (interquartile range) YMRS score was 2.0 (0–5.0), and 52 (28.2%) participants were in a hypomanic state. The prevalence of a hypomanic state was significantly higher in the participants with an average light intensity at night exposure of ≥3 lux than in those with <3 lux (36.7% versus 21.9%; P = .02). In multivariable logistic regression analysis adjusted for BD type, depressive symptoms, sleep duration, and daytime physical activity, the odds ratio (OR) for a hypomanic state was significantly higher for the participants with an average light intensity at night exposure of ≥3 lux than for those with <3 lux (OR: 2.15, 95% confidence interval: 1.09–4.22, P = .02). This association remained significant at the cutoff value of YMRS score ≥6 (OR: 2.51, 95% confidence interval: 1.15–5.46; P = .02). The findings of this study indicate bedroom light exposure at night is significantly associated with manic symptoms in BD patients. Although the results of this cross-sectional investigation do not necessarily imply causality, they may serve to inform beneficial nonpharmacological intervention and personalized treatment of BD patients.     

Nocturnal sleeping habits of the Yunnan snub‐nosed monkey in Xiangguqing,China

Weather, predation, and social organization are hypothesized to influence sleeping habits of nonhuman primates at night. To investigate how the Yunnan snub‐nosed monkey (Rhinopithecus bieti) prepares for and behaves during cold nights in their harsh alpine forest habitat (above 3,000 m), we studied the sleeping habits of the 171 one‐male units (OMU) in one group for 12 months at Xiangguqing in the Baimaxueshan Nature Reserve, China. It took 20.2 min from the time the study group entered a sleeping site until they fell asleep. This duration was consistent over seasons. On average, sleeping time was 11.5 hr per night over the year. Seasonal mean lengths of sleeping time varied significantly, however, and ranged from 10 to 13 hr per night, correlating with night length. Two sleeping styles were distinguishable: solitary sleeping and huddled sleeping. That adult males in OMUs principally slept alone. This is likely to reflect night‐time guarding behavior. Female–juvenile and female–infant dyadic huddles were the most prevalent sleeping unit (42% of all observed data), and the monkeys employed female‐biased huddling during nocturnal sleep. Huddled sleeping group size showed significant seasonal variation, with the largest huddle (eight individuals) occurring in winter. Climate and social organization profoundly influence the nocturnal sleeping habits of R. bieti, while huddling behavior may help shield animals from cold nights and provide additional protection against predators. Am. J. Primatol. 72:1092–1099, 2010. © 2010 Wiley‐Liss, Inc.     

Evening preference is related to the incidence of depressive states independent of sleep-wake conditions

Although evening preference has recently been identified as a risk factor for depression, it has not been substantiated whether evening preference is a direct risk factor for depressive states, or if it is associated secondarily through other factors, such as delayed sleep timing and shortened sleep duration. The objective of this study is to investigate associations in Japanese adult subjects between evening preference and incidence of depressive states, adjusting for various sleep parameters related to depressive states. The Morningness-Eveningness Questionnaire (MEQ), the Pittsburgh Sleep Quality Index (PSQI), and the Center for Epidemiologic Studies Depression Scale (CES-D) were administered to 1170 individuals (493 males/677 females; mean and range 38.5 and 20-59 yrs) to assess their diurnal preferences, sleeping states, and presence of depression symptoms. Subjects were classified into five chronotypes based on MEQ scores. Evening preference was associated with delayed sleep timing, shortened sleep duration, deteriorated subjective sleep quality, and worsened daytime sleepiness. Logistic regression analysis demonstrated that the extreme evening type (odds ratio [OR]?=?1.926, p?=?.018) was associated with increased incidence of depressive states and that the extreme morning type (OR?=?0.342, p?=?.038) was associated with the decreased incidence of depressive states, independent of sleep parameters, such as nocturnal awakening (OR?=?1.844, p?相似文献   

Sleep quality and methylation status of core circadian rhythm genes among nurses and midwives

Poor sleep quality or sleep restriction is associated with sleepiness and concentration problems. Moreover, chronic sleep restriction may affect metabolism, hormone secretion patterns and inflammatory responses. Limited recent reports suggest a potential link between sleep deprivation and epigenetic effects such as changes in DNA methylation profiles. The aim of the present study was to assess the potential association between poor sleep quality or sleep duration and the levels of 5-methylcytosine in the promoter regions of PER1, PER2, PER3, BMAL1, CLOCK, CRY1 CRY2 and NPAS2 genes, taking into account rotating night work and chronotype as potential confounders or modifiers. A cross-sectional study was conducted on 710 nurses and midwives (347 working on rotating nights and 363 working only during the day) aged 40–60 years. Data from in-person interviews about sleep quality, chronotype and potential confounders were used. Sleep quality and chronotype were assessed using Pittsburgh Sleep Quality Questionnaire (PSQI) and Morningness–Eveningness Questionnaire (MEQ), respectively. Morning blood samples were collected. The methylation status of the circadian rhythm genes was determined via quantitative methylation-specific real-time PCR assays (qMSP) reactions using DNA samples derived from leucocytes. The proportional odds regression model was fitted to quantify the relationship between methylation index (MI) as the dependent variable and sleep quality or sleep duration as the explanatory variable. Analyses were carried out for the total population as well as for subgroups of women stratified by the current system of work (rotating night shift/day work) and chronotype (morning type/intermediate type/evening type). A potential modifying effect of the system of work or the chronotype was examined using the likelihood ratio test. No significant findings were observed in the total study population. Subgroup analyses revealed two statistically significant associations between a shorter sleep duration and 1) methylation level in PER2 among day workers, especially those with the morning chronotype (OR = 2.31, 95%CI:1.24–4.33), and 2) methylation level in CRY2 among subjects with the intermediate chronotype, particularly among day workers (OR = 0.52, 95%CI:0.28–0.96). The study results demonstrated a positive association between average sleep duration of less than 6 hours and the methylation level of PER2 among morning chronotype subjects, and an inverse association for CRY2 among intermediate chronotype subjects, but only among day workers. Both the system of work and the chronotype turned out to be important confounders and modifiers in a number of analyses, making it necessary to consider them as potential covariates in future research on sleep deficiency outcomes. Further studies are warranted to explore this under-investigated topic.     

Sleep parameters among offshore workers: an initial assessment in the Campos Basin, Rio De Janeiro, Brazil

Shift work has potentially adverse effects on health, particularly on sleep. The purpose of the present study was to assess sleep parameters among personnel working in oil and gas offshore installations in the Campos Basin, Rio de Janeiro, Brazil. One hundred and seventy-nine subjects were asked to complete a sleep questionnaire with multiple-choice answers. Offshore workers were divided into two groups according to their work schedule: (1) fixed daytime workers (n = 86; age: 35.8+/-9.6 yrs) and (2) shift (n = 87) or night (n = 6) workers (total n = 93; age: 37.7+/-9.7 yrs). Shift/night workers reported poor sleep more frequently than the daytime workers (20.4% vs. 1.2%, p < 0.01), as well as habitual difficulty in falling asleep (15.1% vs. 4.7%, p<0.01), long latency of sleep onset (28% vs. 7%, p<0.01), fragmented sleep (45.2% vs. 16.3%, p<0.01), short sleep episodes (44.1% vs. 16.3%, p < 0.01), irregular bedtimes (29.0% vs. 12.8%, p < 0.01), and feeling tired upon awakening (15.1% vs. 3.5%, p < 0.01). Habitual napping and loud snoring were reported twice as often in shift/night than in day workers (p < 0.01). Nightmares, somnambulism, and unpleasant feeling in the legs were equality reported by both groups (p > 0.05). Few offshore workers had sought medical help for their sleep problems. A higher number of shift/night workers reported feelings of sadness compared with day workers (26.9% vs. 9.3%, p < 0.01). The findings of this study show that subjective reports of sleep-related problems are quite common among Brazilian offshore shift workers. Reliance on self-reported sleep problems and a cross-sectional design are the main limitations of our study.     

The Prognostic Value of the Work Ability Index for Sickness Absence among Office Workers

BackgroundThe work ability index (WAI) is a frequently used tool in occupational health to identify workers at risk for a reduced work performance and for work-related disability. However, information about the prognostic value of the WAI to identify workers at risk for sickness absence is scarce.ObjectivesTo investigate the prognostic value of the WAI for sickness absence, and whether the discriminative ability differs across demographic subgroups.MethodsAt baseline, the WAI (score 7-49) was assessed among 1,331 office workers from a Dutch financial service company. Sickness absence was registered during 12-months follow-up and categorised as 0 days, 0<days<5, 5≤days<15, and ≥15 days in one year. Associations between WAI and sickness absence were estimated by multinomial regression analyses. Discriminative ability of the WAI was assessed by the Area Under the Curve (AUC) and Ordinal c-index (ORC). Test characteristics were determined for dichotomised outcomes. Additional analyses were performed for separate WAI dimensions, and subgroup analyses for demographic groups.ResultsA lower WAI was associated with sickness absence (≥15 days vs. 0 days: per point lower WAI score OR=1.27; 95%CI 1.21-1.33). The WAI showed reasonable ability to discriminate between categories of sickness absence (ORC=0.65; 95%CI 0.63-0.68). Highest discrimination was found for comparing workers with ≥15 sick days with 0 sick days (AUC=0.77) or with 1-5 sick days (AUC=0.69). At the cut-off for poor work ability (WAI≤27) the sensitivity to identify workers at risk for ≥15 sick days was 7.5%, the specificity 99.6%, and the positive predictive value 82%. The performance was similar across demographic subgroups.ConclusionsThe WAI could be used to identify workers at high risk for prolonged sickness absence. However, due to low sensitivity many workers will be missed. Hence, additional factors are required to better identify workers at highest risk.     

Job stress, social support at work, and insomnia in Japanese shift workers

A cross-sectional study was conducted to clarify the contribution of psychological job stress to insomnia in shift workers. A self-administered questionnaire concerning job stress, sleep, depressive symptoms and lifestyle factors was submitted to a sample of 530 rotating shift workers of age 18-59 years (mean age 27) in an electric equipment manufacturing company. Perceived job stress, i.e., job demands, job control and social support at work, was assessed using the Japanese version of the Job Content Questionnaire. Insomnia was regarded as prevalent if the workers had at least one of the following symptoms in the last year; less than 30 minutes to fall asleep, difficulty in maintaining sleep, or early morning awakening almost everyday. Overall prevalence was 37.8%. Logistic regression analyses while adjusting relevant factors showed that lower social support at work was significantly associated with a greater risk of insomnia than the higher social support (adjusted OR 2.5). Higher job strain with lower social support at work increased the risk, compared to lower strain with higher support at work (crude OR 1.8; adjusted OR 1.5). Our findings suggest the low social support at work independently associated with insomnia in shift workers.     

Relationship between shift work schedule and self-reported sleep quality in Chinese employees

Few studies have reported on the effects of fixed and rotating shift systems on the prevalence of sleep disturbance. Thus, in this study, the relationships between different work schedules and sleep disturbance in Chinese workers were investigated. A total of 2180 workers aged 19–65 years responded to the self-report questionnaire on shift work schedule (fixed day-shift, fixed night-shift, two-shift or three-shift system), working hours a day, and working days a week, physical effort, subjective sleep quality and subjective mental state. It was found that the rotating shift workers, namely, two- and three-shift workers, exhibited higher risks of sleep disturbance than with the fixed day-shift workers did (OR 1.37; 95% CI 1.07to 1.74; and OR 2.19; 95% CI 1.52 to 3.15, respectively). The risk was particularly high among two- or three-shift workers who worked more than 8 hours a day or more than 5 days a week and among three-shift workers who reported both light and heavy physical effort at work. Moreover, the two- and three-shift workers (rotating shift workers) suffered from poorer sleep quality than the fixed night shift workers did (OR 1.84; 95% CI 1.01 to 3.32; and OR 2.94; 95% CI 1.53 to 5.64, respectively). Consequently, rotating shift work (two- and three-shift work) is a risk factor for sleep disturbance, and the fixed work rhythm may contribute to the quality of sleep.     

Relationship between sleep duration and arterial stiffness in a multi-ethnic population: The HELIUS study

We examined the relationship between sleep duration and arterial stiffness among a multi-ethnic cohort, and whether the associations differed among ethnic minority groups in the Netherlands. Data were derived from 10 994 participants (aged 18–71 years) of the Healthy Life in an Urban Setting (HELIUS) study. Self-reported sleep duration was categorized into: short (<7 h/night), healthy (7–8 h/night) and long (≥9 h/night). Arterial stiffness was assessed by duplicate pulse-wave velocity (PWV in m/s) measurements using the Arteriograph system. The association of sleep duration with PWV was analysed using linear regression (β) with 95% confidence interval (CI). Results showed that neither short nor long sleep was related to PWV in all ethnic groups, except for long sleep in Dutch men which was associated with higher PWV (indicating stiffer arteries) after adjustment for potential confounders (β = 0.67, 95%CI, 0.23–1.11). Our study showed no convincing evidence that sleep duration was related to arterial stiffness among various ethnic groups. The link between sleep duration and cardiovascular outcomes does not seem to operate through arterial stiffness. Further research is needed to consolidate these findings.     

Shiftwork and Sickness Absence Among Police Officers: The BCOPS Study

Shiftwork, regarded as a significant occupational stressor, has become increasingly prevalent across a wide range of occupations. The adverse health outcomes associated with shiftwork are well documented. Shiftwork is an integral part of law enforcement, a high-stress occupation with elevated risks of chronic disease and mortality. Sickness absence is an important source of productivity loss and may also serve as an indirect measure of workers’ morbidity. Prior studies of shiftwork and sickness absenteeism have yielded varying results and the association has not been examined specifically among police officers. The objective of this study was to compare the incidence rate of sick leave (any, ≥3 consecutive days) among day-, afternoon-, and night-shift workers in a cohort of police officers and also examine the role of lifestyle factors as potential moderators of the association. Participants (N?=?464) from the Buffalo Cardio-Metabolic Occupational Police Stress (BCOPS) study examined between 2004 and 2009 were used. Daily work history records that included the shift schedule, number of hours worked, and occurrence of sick leave were available for up to 15 yrs starting in 1994 to the date of the BCOPS study examination for each officer. Poisson regression analysis for ungrouped data was used to estimate incidence rates (IRs) of sick leave by shift, and comparison of IRs across shifts were made by computing incidence rate ratios (IRRs) and their 95% confidence intervals (CIs). Sick leave occurred at a higher rate on the night shift (4.37 per 10?000 person-hours) compared with either day (1.55 per 10?000 person-hours) or afternoon (1.96 per 10?000 person-hours) shifts. The association between shiftwork and sickness absence depended on body mass index (BMI). For overweight individuals (BMI?≥?25?kg/m²), the covariate-adjusted incidence rate of sick leave (≥1 day) was twice as large for night-shift officers compared with those working on the day (IRR?=?2.29, 95% CI: 1.69–3.10) or afternoon (IRR?=?1.74, 95% CI: 1.29–2.34) shift. The IR of three or more consecutive days of sick leave was 1.7 times larger for those working on night shift (IRR?=?1.65, 95% CI: 1.17–2.31) and 1.5 times larger for those working on afternoon shift (IRR?=?1.50, 95% CI: 1.08–2.08) compared with day shiftworkers. For subjects with normal BMI (<25?kg/m²), the incidence rates of sick leave did not differ significantly across shifts. In conclusion, shiftwork is independently associated with sickness absence, with officers who work the night shift having elevated incidence of sick leave. In addition, overweight officers who work the night shift may be at additional risk for sickness absence.     

An endogenous circadian rhythm in sleep inertia results in greatest cognitive impairment upon awakening during the biological night

Sleep inertia is the impaired cognitive performance immediately upon awakening, which decays over tens of minutes. This phenomenon has relevance to people who need to make important decisions soon after awakening, such as on-call emergency workers. Such awakenings can occur at varied times of day or night, so the objective of the study was to determine whether or not the magnitude of sleep inertia varies according to the phase of the endogenous circadian cycle. Twelve adults (mean, 24 years; 7 men) with no medical disorders other than mild asthma were studied. Following 2 baseline days and nights, subjects underwent a forced desynchrony protocol composed of seven 28-h sleep/wake cycles, while maintaining a sleep/wakefulness ratio of 1:2 throughout. Subjects were awakened by a standardized auditory stimulus 3 times each sleep period for sleep inertia assessments. The magnitude of sleep inertia was quantified as the change in cognitive performance (number of correct additions in a 2-min serial addition test) across the first 20 min of wakefulness. Circadian phase was estimated from core body temperature (fitted temperature minimum assigned 0 degrees ). Data were segregated according to: (1) circadian phase (60 degrees bins); (2) sleep stage; and (3) 3rd of the night after which awakenings occurred (i.e., tertiary 1, 2, or 3). To control for any effect of sleep stage, the circadian rhythm of sleep inertia was initially assessed following awakenings from Stage 2 (62% of awakening occurred from this stage; n = 110). This revealed a significant circadian rhythm in the sleep inertia of cognitive performance (p = 0.007), which was 3.6 times larger during the biological night (circadian bin 300 degrees , approximately 2300-0300 h in these subjects) than during the biological day (bin 180 degrees , approximately 1500-1900 h). The circadian rhythm in sleep inertia was still present when awakenings from all sleep stages were included (p = 0.004), and this rhythm could not be explained by changes in underlying sleep drive prior to awakening (changes in sleep efficiency across circadian phase or across the tertiaries), or by the proportion of the varied sleep stages prior to awakenings. This robust endogenous circadian rhythm in sleep inertia may have important implications for people who need to be alert soon after awakening.     

Relationships between daytime sleepiness and sleep quality,duration, and phase among school-aged children: a cross-sectional survey

A cross-sectional survey was conducted to simultaneously evaluate sleep quality, duration, and phase in school-aged children and correlations between each dimension of sleep and daytime sleepiness were comprehensively examined. A cross-sectional survey was conducted with school-aged children enrolled in four public elementary schools in Joetsu city, Niigata prefecture in Japan (n = 1683). Among the collected responses (n = 1290), 1134 valid responses (547 boys and 587 girls) were analyzed (valid response rate was 87.90%). Data on daytime sleepiness, sleep quality (problems in sleeping at night), sleep duration (the average sleeping time during a week), and sleep phase (sleep timing: bedtime and rising time on weekdays, and sleep regularity: differences in bedtime and rising time between on weekdays and weekends) were collected. The results of multivariate logistic regression analysis indicated that the following dimensions were significantly correlated with daytime sleepiness: the decline in sleep quality [adjusted odds ratio (AOR) = 2.62, 95% confidence interval (CI) = 1.71–4.00], bedtime after 21:30 on weekdays (AOR = 1.58, 95% CI = 1.15–2.18), bedtime delay on weekends, compared to weekdays (AOR = 1.75, 95% CI = 1.27–2.41), and bedtime advance on weekends, compared to weekdays (AOR = 3.33, 95% CI = 1.78–6.20). Sleep dimensions that significantly affected daytime sleepiness in school-aged children are sleep quality, bedtime-timing, and regularity of bedtime. It is important to detect problems in night sleep and establish treatments, as well as to provide support for early bedding on weekdays and for a regular bedtime both on weekdays and on weekends to prevent daytime sleepiness in school-aged children.