Health consequences of shift work and insufficient sleep

Shift work is commonly increasing, and some physiological changes occur as workers sleep less and their circadian rhythms are disrupted. This umbrella review not only summarizes the evidence but also evaluates the validity of the associations of shift work with different health outcomes. We searched the MEDLINE, Web of Science, and Embase databases from their inception to April 25, 2020. For each systematic review and/or meta-analysis, we estimated the summary effect size, the 95% confidence interval, the 95% prediction interval, the between-study heterogeneity, evidence of small-study effects, and evidence of excess-significance bias. Eight eligible systematic reviews and meta-analyses were identified, providing data on 16 associations. We observed highly suggestive evidence for associations between shift work and myocardial infarction (having ever vs having never done shift work) and diabetes mellitus incidence (per 5-year increment in shift work). Furthermore, we observed suggestive evidence for an association between shift work and diabetes mellitus incidence (having ever vs having never done shift work). Two health outcomes, including prostate cancer incidence (having ever vs having never done shift work and rotating night shift work vs daytime work) and colorectal cancer incidence (longest vs shortest shift work time), were only supported by weak evidence. This umbrella review found that shift work was associated with several health outcomes with different levels of evidence. Associations for myocardial infarction and diabetes mellitus incidence were supported by highly suggestive evidence. Registry: PROSPERO; Identifier: CRD42020188537. Wu Q-J, Sun H, Wen Z-Y, etal. Shift work and health outcomes: an umbrella review of systematic reviews and meta-analyses of epidemiological studies. J Clin Sleep Med. 2022;18(2):653-662.

Does shift work cause cancer?

<sec><st>Introduction</st> Usually night and shift work have been associated with insomnia and fatigue. The current industry model implies the existence of many groups of night workers. For this reason we consider of interest to conduct a systematic review to evaluate the relationship between shift or night work as risk factors for health. </sec> <sec><st>Objectives</st> Evaluate the relationship between shift or night work as a risk factor for health and performance for working. </sec> <sec><st>Methodology</st> Literature review from Pubmed database (01/10/2015) with keywords (“sleep disorder or insomnia”) and (occupational or workplace) and active filters: last 5 years, human, Spanish, English or French. 571 publications were found, of which 141 were selected from title critical lecture (3 independent reviewers, and articles were selected if 2 or 3 of the 3 reviewers agree). Critical lecture of abstracts for 5 reviewers was performed and 35 of the 141 were selected. 6 of 141 papers were not found. </sec> <sec><st>Results</st> In this review, a relationship between shift and night work with loss of sleep (OR 1.17-4.1) and increased accidents (OR 1.62) is observed. Time control, sleep 2–3 hours during the night shift, and working maximum 3 consecutive night days, are also seen as protective factors. </sec> <sec><st>Conclusions</st> Night and shift work is related to insomnia and fatigue, which leads to a reduced work capacity and increased accidents; although it seems that it does not lead to premature ageing. It would be desirable to identify profiles of night workers (owls) and evaluate the effects of the double presence with these types of work, especially in women. There is controversy as to whether these jobs can cause anxiety disorder and/or depression. </sec>

<h3>Introduction</h3> Usually night and shift work have been associated with insomnia and fatigue. The current industry model implies the existence of many groups of night workers. For this reason we consider of interest to conduct a systematic review to evaluate the relationship between shift or night work as risk factors for health. <h3>Objectives</h3> Evaluate the relationship between shift or night work as a risk factor for health and performance for working. <h3>Methodology</h3> Literature review from Pubmed database (01/10/2015) with keywords (“sleep disorder or insomnia”) and (occupational or workplace) and active filters: last 5 years, human, Spanish, English or French. 571 publications were found, of which 141 were selected from title critical lecture (3 independent reviewers, and articles were selected if 2 or 3 of the 3 reviewers agree). Critical lecture of abstracts for 5 reviewers was performed and 35 of the 141 were selected. 6 of 141 papers were not found. <h3>Results</h3> In this review, a relationship between shift and night work with loss of sleep (OR 1.17-4.1) and increased accidents (OR 1.62) is observed. Time control, sleep 2–3 hours during the night shift, and working maximum 3 consecutive night days, are also seen as protective factors. <h3>Conclusions</h3> Night and shift work is related to insomnia and fatigue, which leads to a reduced work capacity and increased accidents; although it seems that it does not lead to premature ageing. It would be desirable to identify profiles of night workers (owls) and evaluate the effects of the double presence with these types of work, especially in women. There is controversy as to whether these jobs can cause anxiety disorder and/or depression.

Langmuir probes are used to determine the electron temperature, electron density, and longitudinal heat flux in the immediate vicinity of the limiter in the T-3M tokamak. (AIP)

The long-term effects of sleep health and shift work on cognitive performance are unclear. In addition, research has been limited by small sample sizes and short follow-up periods. We conducted one of the largest examinations of the longitudinal influence of sleep health dimensions and shift work on cognitive performance in people of middle and old age using data from the UK Biobank. The hypothesis was that poor sleep health and shift work would predict lower cognitive performance. Self-reported sleep duration, daytime sleepiness, insomnia symptoms, chronotype and shift work status were assessed as predictors at baseline. Cognitive performance was operationalised by a touchscreen test battery at follow-up between 7.4 ± 2.2 and 9.0 ± 0.9 years after baseline assessment, depending on the specific task. Models were performed for each cognitive domain including relevant confounders (e.g., depression). The alpha level was set at p<0.01 for all analyses. The study sample comprised 9,394 participants for the reasoning task, 30,072 for the reaction time task, 30,236 for the visual memory task, 2,019 for the numeric memory task and 9,476 for the prospective memory task. Shift work without night shifts (ß= -2.0x10- 1 ± 6.5x10- 2, p=0.002) and with night shifts (ß= -1.9x10- 1 ± 7.2x10- 2, p=0.010) predicted a significantly reduced performance in the reasoning task. Short sleep duration (ß= -2.4x10- 1 ± 7.9x10- 2, p=0.003) and shift work without night shifts (ß= -3.9x10- 1 ± 1.2x10- 1, p=0.002) predicted a significantly lower performance in the task probing prospective memory. Our results suggest that, after controlling for confounding variables, shift work and short sleep duration are important predictors for cognitive performance in people of middle and old age. Further work is required to examine causal mechanisms of the observed associations.

Work-related stress and health—risks, mechanisms and countermeasures

Position statement: Reducing fatigue associated with sleep deficiency and work hours in nurses

Working in shifts, especially if night shifts are included, is associated with many adverse health effects varying from gastrointestinal disturbances to cardiovascular diseases, metabolic syndrome, and type 2 diabetes (1-4). The exact mechanisms for these associations are not firmly established (5). Short-term sleep restriction is known to induce insulin resistance and, for example, disturbances in fat metabolism (6), and shift workers are known to suffer from sleep loss. It is plausible that lifestyle factors related to shift work play a role as well. The accumulation of body fat leading to overweight and obesity is one of the key factors behind the development of metabolic disturbances in general population, and we can assume it to be so also among shift workers (7). There seems to be even a dose-response association, with an increasing trend in weight with increasing duration of shift work (8). But what exactly is it in shift work that predisposes those who do it to weight gain? And can we do something about it?In their systematic review of longitudinal studies, Van Drongelen et al (9) found a strong evidence for a crude association between shift work exposure and body weight increase; however the confounder-adjusted associations were found to be inconclusive. This indicates that it is not shift work per se but other factors related to or associated with shift work that lead to body fat accumulation.On the other hand, in a recent systematic review, Bonham et al (10) concluded that energy intake does not differ between day and shift workers, and suggest that other factors such as circadian misalignment, meal timing, food choice and diurnal variation of energy metabolism at night may be responsible for the increased rates of obesity observed among shift workers. In general, only minor differences in nutrient intake between day and shift workers have been identified, and the results have been somewhat conflicting. It has been suggested that shift workers have more eating events per day than day workers (11), and it seems that shift workers make more unfavorable food choices than day workers do, preferring snack foods and sugary drinks (11, 12). In a recent study, shift working men were less likely to consume vegetables and fruits daily and women had higher intake of saturated fat compared with day workers (13).In a paper by Hulsegge et al (14) in this issue, shift workers were found to have a higher energy intake than day workers (56 kcal/d) and a slightly higher consumption of grains, dairy products, meat and fish and lower consumption of cakes and biscuits. No difference in savory snacks, sweets, soft drinks or juices were found. The difference in energy intake was largest for shift workers with >5 night shifts/month, who consumed 103 kcal/d more than day workers. The authors conclude that shift and day workers' dietary quality is the same, but suggest that a higher energy intake among shift workers may be one of the causes of shift-work-induced overweight, obesity, and other adverse health outcomes; a reasonable suggestion if we acknowledge as fact that overweight indeed develops as a result of positive energy balance.The study included a relatively large population-based sample of 683 and 7173 shift and day workers, respectively from the original cohort of 40 010 men and women. The analyses were cross-sectional, with dietary data collection based on a 178-item semi-quantitative food frequency questionnaire for the past year diet and retrospective data collection on work schedule 14-20 years earlier. The analyses were adjusted for several confounders, including age, sex, smoking, physical activity, and body mass index (BMI). No differences were presented for clinical risk factors, except that shift workers had slightly higher BMI compared with day workers. BMI is a crude measure of body adiposity, but does not tell anything about the actual body size, which is the most important predictor of energy expenditure (15). …

The purpose of our study was mainly to explore the effect of different shift work on cognitive and executive performance in a real clinical environment among nurses from China. Working in shifts can disrupt circadian rhythm, resulting in reduced sleep duration, which can have a detrimental effect on cognitive function. To provide continuous service for patient care, shift work is often a special requirement for nurses. The Stroop test can be used to measure selective attention and reaction time during executive function. However, there have been limited studies about the effect of shift work on the cognitive performance of nurses by Stroop tests. Additionally, no study has been conducted in nurses working in shifts from China. Registered nurses in general ward, Department of Neurology, from West China Hospital of Sichuan University, were eligible and consecutively included if they were simultaneously responsible for the day, evening and night shifts on the shift work schedule. A fatigue questionnaire and Stroop tests were performed for each subject separately before and after three working shifts (morning, evening and night shift) to measure changes in fatigue, reaction time and accuracy. Eighteen registered nurses (4 males and 14 females) were included in our study, with a median age of 25 years old. The fatigue degree was significantly increased after day and evening shifts (p = .015 and <.001, respectively). Compared with those in the preshifts, the reaction time in the neutral task and incongruent task was significantly quicker after the day shift (p = .001, p < .001) and night shift (p = .008, .019). In contrast, the reaction time after the evening shift was mildly increased, although without significance. There was no significant difference in accuracy among the three different working shifts. In addition, there was a negative correlation between the fatigue score and reaction time on the incongruent task in the Stroop test before the day shift (r = -.542, p = .020). The fatigue score in the postday shift was found to be inversely related to working hours in the daytime (r = -.500, p = .034). Our study showed that increased fatigue was found in nurses after day and evening shifts, and shift work can affect the reaction time after the evening shift. However, there was no significant difference in accuracy and a high level of attention could be maintained among the three working shifts, suggesting a highly developed sense of responsibility in our nurses. In addition to focusing on the common adverse effects of evening or night shifts on nurses, fatigue in the day shift should be paid special attention to by the leadership in the nursing management. Also, nurse managers can implement specific strategies to reduce fatigue after the day shift by shortening the working hours in the daytime appropriately, setting rest periods in the day shift or dividing nurses into morning and afternoon shifts.

Studies have shown that some diseases are highly prevalent in shift workers, such as nutritional, metabolic, gastrointestinal, psychological and sleep disorders. In addition, it has been documented a high occurrence of various symptoms among these workers, such as pain, insomnia, sleepiness, heartburn, fatigue, weight gain, weight loss and irritability. Therefore, we hypothesized that shift workers consume more medications than people who work on regular times. The aim of this study was to evaluate the use of medications between workers who work in different shifts. A total of 1,099 shift workers of a Brazilian poultry processing agribusiness who had not been previously reported chronic diseases were included in the study. All volunteers worked 10 hours daily in one of the following shifts: early morning, day, evening and night shift. A questionnaire was used to assess sociodemographic characteristics, medical history and lifestyle habits (patterns of sleep, physical activity and tobacco use). The use of medication - including self-medication was evaluated by self-reported daily habitual use. It was also measured the waist circumference, weight and height, and the body mass index (BMI) was calculated. Of the total, 67% of workers reported to consume any medication every day. The most consumed daily medication classes were: analgesics (45.9%), muscle relaxants (44.2%), hormones (17.3%), antacids (15.3%), non-steroidal anti-inflammatory (8,1% ) and hypnotics (2.6%). The prevalence of self-medication was higher between evening workers (54.8%), followed by early morning (51.9%), night (51.5%) and day workers (34.3%) (p <0.001). Night shift workers had, in relation to workers from other shifts: lower median of total sleep hours (p <0.001), higher frequency of workers with inadequate sleep pattern (p <0.001), higher median of waist circumference (p = 0.004), higher frequency of smokers (p = 0.002) and a higher frequency of sedentary (p = 0.006). Multivariate logistic regression analysis indicated that night shift is positively associated to the use of muscle relaxants (OR = 1.39, 95% CI 1.03-2.07, p = 0.034) and hypnotics (OR = 1.45 , 95% CI 1.55-2.08, p = 0.003); work in the early morning shift is positively associated to the use of muscle relaxants (OR = 1.40, 95% CI 1.02-1.93, p = 0.037), poor sleep pattern is positively associated to the use of muscle relaxants (OR = 1.60, 95% CI 1.59-1.99; p = 0.032) and hypnotics (OR = 1.55, 95% CI 1.56-2.06; p = 0.003); being female is positively associated to the consumption of analgesics (OR = 2.80, 95% CI 2.11-3.73, p = 0.001), muscle relaxants (OR = 1.93, 95% CI 1.44-2,59, p = 0.001), hormones (OR = 4.50, 95% CI 14.01-737.2, p = 0.001) and antacids (OR = 2.58, 95% CI: 1.61-4.12, p = 0.001); and being obese is positively associated to the consumption of muscle relaxants (OR = 1.51, 95% CI 1.07-2.13, p = 0.019). These results demonstrate that shift workers have a high consumption of medications, and the self-medication practice and consumption muscle relaxants, hormones, antacids and hypnotics were dependent on the shift work. These results pointed to the need to carry out intervention programs related to improvement of the health quality and proper use of medications in these workers.

Sleep disorders in physicians who perform shift work can result in increased risks of health problems that negatively impact performance and patient safety. Even those who cope well with shift work are likely to suffer from sleep disorders. The aim of this manuscript is to discuss possible causes, contributing factors and consequences of sleep disorders in physicians and to identify measures that can improve adaptation to shift work and treatment strategies for shift work-associated sleep disorders. The risk factors that influence the development of sleep disorders in physicians are numerous and include genetic factors (15 % of the population), age (> 50 years), undiagnosed sleep apnea,, alcohol abuse as well as multiple stress factors inherent in clinical duties (including shift work), research, teaching and family obligations. Several studies have reported an increased risk for medical errors in sleep-deprived physicians. Shift workers have an increased risk for psychiatric and cardiovascular diseases and shift work may also be a contributing factor to cancer. A relationship has been reported not only with sleep deprivation and changes in food intake but also with diabetes mellitus, obesity, hypertension and coronary heart disease. Nicotine and alcohol consumption are more frequent among shift workers. Increased sickness and accident rates among physicians when commuting (especially after night shifts) have a socioeconomic impact. In order to reduce fatigue and to improve performance, short naps during shiftwork or naps plus caffeine, have been proposed as coping strategies; however, napping during adverse circadian phases is less effective, if not impossible when unable to fall asleep. Bright and blue light supports alertness during a night shift. After shiftwork, direct sunlight exposure to the retina can be avoided by using dark sunglasses or glasses with orange lenses for commuting home. The home environment for daytime sleeping after a night shift should be very dark to allow endogenous melatonin secretion, which is a night signal and supports continuous sleep. Sleep disorders can be treated with timed light exposure, as well as behavioral and environmental strategies to compensate for sleep deprivation. Fatigue due to sleep deprivation can only be systematically treated with sleep.

BackgroundThe SNORE (Sleep Deprivation among Night shift health staff On Rotation-Evaluation) study evaluated the effects of sleep deprivation on healthcare professionals working rotational night shifts. Given the association between sleep deprivation and cognitive impairment, this sub-study examined the prevalence of cognitive impairment and its relationship with sleep deprivation in a tertiary care hospital.MethodsA cross-sectional study included 293 healthcare workers (doctors, nurses, paramedics). Cognitive function was assessed using the Montreal Cognitive Assessment (MoCA) during day and night shifts. Sleep deprivation was evaluated via the Epworth Sleepiness Scale (EPSS) and self-reported sleep hours. Statistical analysis employed the Wilcoxon signed-rank test for shift-wise cognitive score comparison and multivariable logistic regression to explore the relationship between sleep deprivation and cognitive impairment.ResultsCognitive impairment prevalence during night shifts was 23.5%, with nurses showing slightly higher rates (26.2%). Cognitive scores were significantly lower during night shifts (median 28) compared to day shifts (median 29). Sleep deprivation was significantly associated with cognitive impairment (adjusted odds ratio [aOR]: 1.78 [1.01–3.16] for EPSS; 9.20 [2.16–39.23] for self-reported sleep hours). Male participants exhibited higher odds of impairment than females (aOR: 2.30 [1.19–4.47]).ConclusionSleep deprivation significantly impacts cognitive function in healthcare workers, with more pronounced effects during night shifts. These findings underscore the urgent need for interventions promoting sleep health and optimizing working conditions in healthcare settings.

Background: The number of older employees in shift and night work has increased significantly in recent years. Furthermore, the proportion of women in shift and night work has increased markedly. This is due to the aging workforce and the expansion of shift work in the tertiary sector. Previous research shows that shift work is often associated with health risks. Against this background, the aim of the present study is to examine the situation of working men and women on the threshold to higher working age with regard to the relationship between shift work and physical health. Methods: We employed data from the study "lidA - leben in der Arbeit" German Cohort Study on Work, Age and Health, a survey of the German baby boom cohorts born in 1959 and 1965 (n=5 637). Linear regression models are used to study the effect of shift work - with and without night work - and of further work exposures on the baby boomers' physical health status. The models control for sleep and health-related behaviour and are stratified by gender. Among women, also the scope of work was taken into account. Results: The results show that male shift workers are burdened by their on average lower occupational status and by physical exposure; female shift workers additionally suffer from high personal effort and low rewards and female part-time shift workers also from overcommitment. Conclusion: Working conditions of shift workers are strongly characterised by work stress. In order to preserve aging shift workers' work ability, some organisational measures seem necessary. In this context, occupational safety and health management as well as opportunities for recovery and encouraging leadership should be considered.

Prostate cancer risk decreases following cessation of night shift work.