Siri Waage

The association between sleep duration, body mass index and metabolic measures in the Hordaland Health Study.

Several studies show that short self‐reported sleep duration is associated with elevated body mass index (BMI). Short sleep duration may change appetite hormones, but whether this also influences metabolic measures like cholesterol and triglycerides is less clear. Furthermore, obesity is linked to increases in blood pressure, and recently, short sleep duration has been shown to be an independent risk factor for hypertension. This is a population‐based cross‐sectional study (The Hordaland Health Study). A subgroup of 8860 subjects, aged 40–45 years, answered a sleep questionnaire. Body weight, height and blood pressure were measured, and non‐fasting blood samples were collected and analyzed for total cholesterol, HDL‐cholesterol and triglycerides. Sleep duration was divided into the following subgroups: <5, 5–5.99, 6–6.99, 7–7.99, 8–8.99 and ≥9 h. The results show that short sleep duration was associated with elevated BMI and increased prevalence of obesity. Similar to BMI, levels of cholesterol, triglycerides, systolic and diastolic blood pressure were higher in subjects with short sleep duration. This co‐variation seemed to be attributed to variables like gender, smoking and BMI. In conclusion, our study confirms a clear association between short sleep duration and elevated BMI and obesity. Furthermore, levels of total cholesterol, HDL‐cholesterol, triglycerides and blood pressure were associated with sleep duration.

Shift Work Disorder in a Random Population Sample – Prevalence and Comorbidities

Few studies have investigated the presence of shift work disorder (SWD) in the general community. We addressed many of the limitations in this literature and present new findings. SWD has been treated as an ‘all or none’ construct but we propose the need to consider the ‘severity’ of the disorder. Using random digit dialling, we randomly recruited 1163 participants. Participants completed an extensive battery of scales and questions concerning work, health and individual differences. Three questions based on the criteria from the International Classification for Sleep Disorders were used to categorise participants with SWD (n = 176). In addition, we asked participants whether SWD interfered with aspects of their life and high ratings were used to define severe shift work disorder (SSWD). The prevalence of SWD was 32.1% among night workers and 10.1% in day workers (p<.001). SSWD was present in 9.1% of night workers and 1.3% of day workers (p<.001). Adjusted logistic regression analyses found significant associations between SWD and night work (OR  = 3.35, CI 2.19-5.12), weekly work hours (OR  = 1.02, CI 1.00–1.04), short sleep (≤6 h; OR  = 2.93, CI 1.94–4.41), languidity (OR  = 1.11, CI 1.06–1.16) and resilience (OR  = 0.56, CI 0.43–0.81). Night work, short sleep, languidity, and hypertension were significantly associated with SSWD. Overall, participants with SSWD slept 0.80 h less than other participants (p<.001). Night work, short sleep and languidity were associated with both SWD and SSWD. Day workers with SWD symptoms reported significantly shorter sleep duration, higher levels of languidity and worked longer working hours compared to day workers without SWD.

Systematic review of the relationship between quick returns in rotating shift work and health-related outcomes

A systematic literature search was carried out to investigate the relationship between quick returns (i.e. 11.0 hours or less between two consecutive shifts) and outcome measures of health, sleep, functional ability and work–life balance. A total of 22 studies published in 21 articles were included. Three types of quick returns were differentiated (from evening to morning/day, night to evening, morning/day to night shifts) where sleep duration and sleepiness appeared to be differently affected depending on which shifts the quick returns occurred between. There were some indications of detrimental effects of quick returns on proximate problems (e.g. sleep, sleepiness and fatigue), although the evidence of associations with more chronic outcome measures (physical and mental health and work–life balance) was inconclusive. Practitioner Summary: Modern societies are dependent on people working shifts. This study systematically reviews literature on the consequences of quick returns (11.0 hours or less between two shifts). Quick returns have detrimental effects on acute health problems. However, the evidence regarding effects on chronic health is inconclusive.

Predictors of shift work disorder among nurses: a longitudinal study

BACKGROUND Shift work is associated with sleep problems and impaired health. The main aim of the present study was to explore predictors of developing shift work disorder (SWD) among Norwegian nurses using a longitudinal design. METHODS A total of 1533 nurses participating in a survey on shift work, sleep and health responded to questionnaires at baseline and at follow-up about two years later. SWD was defined as problems of excessive sleepiness and/or complaints of insomnia related to the work schedule. RESULTS AND CONCLUSIONS There was a significant reduction (p < 0.001) in the prevalence of SWD from baseline to follow-up, from 35.7% to 28.6%. Logistic regression analyses showed significant risks of having SWD at follow-up and the following variables measured at baseline: number of nights worked the last year (OR = 1.01, 95% CI = 1.01-1.02), having SWD (OR = 5.19, 95% CI = 3.74-7.20), composite score on the Epworth Sleepiness Scale (OR = 1.08, 95% CI = 1.04-1.13), use of melatonin (OR = 4.20, 95% CI = 1.33-13.33), use of bright light therapy (OR = 3.10, 95% CI 1.14-8.39), and symptoms of depression measured by the Hospital Anxiety and Depression Scale (OR = 1.07, 95% CI = 1.00-1.14). In addition, leaving night work between baseline and follow-up was associated with a significantly reduced risk of SWD at follow-up (OR = 0.12, 95% CI = 0.07-0.22).

Subjective and objective sleepiness among oil rig workers during three different shift schedules

OBJECTIVES Examine sleepiness in three different shift work schedules (within-subject design) in the offshore oil industry. METHODS Sleepiness was measured in 19 oil rig workers, using subjective (Karolinska Sleepiness Scale; Accumulated Time with Sleepiness) and objective measures (reaction time). The work schedule consisted of two weeks of 12 h day work (day shifts), two weeks of 12 h night work (night shifts), and two weeks of swing shift work (one week of night work followed by one week of day work). RESULTS Sleepiness was highest during the first days of night and swing shifts, and also in the middle of the swing shift work period, but gradually decreased as the days on the night shift progressed. While at home following the two-week work period, the workers reported more subjective sleepiness after night shift than after day or swing shifts. Reaction time tests during the work period showed no significant differences between the shift schedules. There was a significant shorter reaction time the last day compared to the beginning or middle of the work period. CONCLUSIONS Subjective sleepiness was higher during the first days of night work compared to day work, and also when the swing shift workers changed from night work to day work in the middle of the two-week work period. Subjective sleepiness was increased at home following night shifts compared to after day and swing shifts, suggesting that swing shift workers adapted their circadian rhythm during their second period of work, during the day shift week, offshore.

Self-reported sleep and health among Norwegian hospital nurses in intensive care units.

AIM AND BACKGROUND Shift work, and especially night work, is associated with poor health. Nurses, work a variety of work schedules including night work. So far, few studies have specifically investigated sleep and health among intensive care nurses. DESIGN AND METHODS We investigated sleep, sleepiness, fatigue, subjective health complaints, anxiety and depression in 150 intensive care nurses (convenience sample representing a response rate of 56·2%). The nurses worked at two major University hospitals in Norway and answered a questionnaire survey. RESULTS The intensive care nurses reported poorer sleep, more sleepiness, more fatigue, more anxiety and more depression compared to normative data. Poor sleep was reported by 70% and excessive sleepiness by 25% of the nurses; however, the design of the study did not allow us to determine the causes underlying these findings. Multiple linear regression analyses showed that age was positively associated with sleep problems, fatigue, subjective health complaints and anxiety and depression. In contrast, shift work experience was negatively associated with sleep problems, suggesting better coping with shift work over time. CONCLUSIONS Nurses working in intensive care units reported poorer sleep, more sleepiness, more fatigue, more anxiety and more depression compared to Norwegian norm groups. Age was positively related to these complaints, whereas shift work experience was negatively related to poor sleep. More studies are needed on strategies to improve sleep and health in nurses.

Subjective and objective sleep and sleepiness among tunnel workers in an extreme and isolated environment: 10-h shifts, 21-day working period, at 78 degrees north

OBJECTIVES The aim of this study was to examine the effects of extended work hours (10 h on, 14 h off for 21 days) on sleep and sleepiness in an extreme and isolated environment in the far north (Spitsbergen, 78 degrees north). We wanted to examine whether sleep duration, sleepiness and other parameters changed over the 3-week working period and whether the parameters differed between day and night shifts. METHODS The work consisted of tunnel construction in Svea, Spitsbergen. The participants worked alternate fixed day shift (06:00-16:00) or fixed night shift (18:00-04:00) for a 21-day work period in a counterbalanced, crossover design. The participants were 25 male workers (age 24-60 years). We used subjective and objective measures of sleep (diary and actigraphy) and a subjective daytime sleepiness and function questionnaire. RESULTS The workers had a high sleep efficiency measured both subjectively and objectively. This did not change across days or between day and night shifts. Total sleep time was significantly shorter (about (1/2) to 1h) during the day shift period than during the night shift period, as measured both subjectively and objectively, but did not differ across days. Subjective ratings of sleepiness did not differ between shifts. CONCLUSIONS There were few differences between the day and night shift periods and across the 21-day working period, as measured both subjectively and objectively. The subjects experienced few problems and seemed to adapt easily to their work schedule. This contrasts with what is usually the case in more conventional shift work situations, where workers do not adapt well, as measured by sleepiness and various sleep parameters.

Short rest periods between work shifts predict sleep and health problems in nurses at 1-year follow-up.

Objectives We investigated whether the number of work shifts separated by less than 11 hours (quick returns) at baseline (T1) could predict health problems in nurses at 1-year follow-up (T2). Methods 1224 nurses responded to a questionnaire-based survey in 2009 (T1) and 2010 (T2). Crude and adjusted logistic regression analyses were completed to assess the association between annual number of quick returns at T1 and the following outcome variables at T2: shift work disorder (SWD), excessive sleepiness (Epworth Sleepiness Scale), pathological fatigue (Chalder Fatigue Scale) and anxiety and depression (Hospital Anxiety and Depression Scale), while controlling for age, gender, the corresponding outcome variable at T1, number of night shifts at T1, change in number of quick returns and number of night shifts from T1 to T2. Results The adjusted analyses showed that the annual number of quick returns at T1 predicted the occurrence of SWD (OR=1.01, 95% CI 1.00 to 1.01) and pathological fatigue (OR=1.01, 95% CI 1.00 to 1.01) at T2. A decreased number of quick returns from T1 to T2 entailed a reduced risk of pathological fatigue (OR=0.67, 95% CI 0.45 to 0.99) at T2. There was no association between quick returns at T1 and excessive sleepiness, anxiety or depression at T2 in the adjusted analyses. Conclusions This is the first longitudinal study investigating the associations between quick returns and future health problems. Quick returns increased the risk of SWD and pathological fatigue at 1-year follow-up. Reducing the number of quick returns from 1 year to the next was related to reduced risk of developing pathological fatigue.

Effects of Shift and Night Work in the Offshore Petroleum Industry: A Systematic Review

Shift and night work are associated with several negative outcomes. The aim of this study was to make a systematic review of all studies which examine effects of shift and night work in the offshore petroleum industry, to synthesize the knowledge of how shift work offshore may affect the workers. Searches for studies concerning effects on health, sleep, adaptation, safety, working conditions, family- and social life and turnover were conducted via the databases Web of Knowledge, PsycINFO and PubMed. Search was also conducted through inspection of reference lists of relevant literature. We identified studies describing effects of shift work in terms of sleep, adaptation and re-adaptation of circadian rhythms, health outcomes, safety and accidents, family and social life, and work perceptions. Twenty-nine studies were included. In conclusion, the longitudinal studies were generally consistent in showing that adaptation to night work was complete within one to two weeks of work, while re-adaptation to a daytime schedule was slower. Shift workers reported more sleep problems than day workers. The data regarding mental and physical health, family and social life, and accidents yielded inconsistent results, and were insufficient as a base for drawing general conclusions. More research in the field is warranted.

Parasomnias are more frequent in shift workers than in day workers

The aim of this study was to investigate whether different shift work schedules were associated with nonrapid eye movement (NREM)- and/or REM-related parasomnias. A total of 2198 nurses with different work schedules participated in a longitudinal cohort study. The parasomnia questions were included in the fourth wave of the data collection, with a response rate of 74.1%. Logistic regression analyses with the different parasomnias as dependent variables were conducted. Nurses working two shift (day and evening) and nurses working three shift (day, evening and night) rotational schedules had increased risk of confusional arousal, a NREM-related parasomnia, compared to nurses working daytime only (odds ratios = 2.10 and 1.71, respectively). Similarly, nurses working two and three shift rotational schedules had increased risk of nightmares, a REM-related parasomnia (odds ratios = 1.64 and 1.57, respectively). The other parasomnias were not significantly associated with work schedule. Working night shifts only was not associated with any of the parasomnias. In conclusion, confusional arousal and nightmares were more commonly reported by nurses working rotational shift work schedules compared to nurses working daytime only. This is likely related to the circadian rhythm misalignment and sleep deprivation caused by such shift schedules.