Beyond the Outbreak of COVID-19: Factors Affecting Burnout in Nurses in Iran.

Background: Nurses working in treating patients with COVID-19 are exposed to various stressors, such as fear of COVID-19, stress, and high workload, leading to burnout. Objectives: This study aimed to identify the level of burnout and its predictors in nurses working in hospitals for COVID-19 patients. Methods: Participants in this study were nurses working in 11 hospitals for COVID-19 patients in the Fars province of Iran. The Maslach burnout and the UK Health and Safety stress questionnaires were used to assess burnout and stress, respectively. Analysis, using multiple regression in the SPSS21 software, aimed to identify the factors affecting burnout. Findings: The mean level of burnout in the nurses at the COVID-19 hospitals was 57 out of 120, and burnout was affected by workload (ß = 0.69, p < 0.001), job stress (ß = 0.25, p < 0.001) and inadequate hospital resources for the prevention of COVID-19 (ß = -0.16, p < 0.001). These three variables explained 87% of the variance in burnout. Conclusions: The burnout of nurses directly exposed to COVID-19 patients is more than nurses in other wards, and workload is the most significant cause of burnout in them. Therefore, necessary measures such as hiring more nurses, reducing working hours and increasing rest periods are necessary to reduce workload. In addition, the job stress of these nurses should be managed and controlled, and the hospital resources needed to prevent this disease should be provided.

Medication Errors in Surgery: A Classification Taxonomy and a Pilot Study in Postcall Residents.

INTRODUCTION: The post-call state in postgraduate medical trainees is associated with impaired decision-making and increased medical errors. An association between post-call state and medication prescription errors for surgery residents is yet to be established. Our objective was to determine whether post-call state is associated with increased proportion of medication prescription errors committed by surgery residents in an academic hospital without a computerized physician order entry (CPOE) system. METHODS: This prospective observational study was conducted at a tertiary academic hospital between June 28 and August 31, 2017. It compared the proportion of medication prescription errors committed by surgery residents in their post-call (PC) and no-call (NC) states. A novel taxonomy was developed to classify medication prescription errors. RESULTS: Sixteen of twenty-one eligible residents (76%) participated in this study. Self-reported hours of sleep per night was significantly higher in the NC group compared to the PC group (6(4-8) vs 2(0-4) hours, P < 0.01). PC residents committed a significantly higher proportion of medication prescription errors versus NC residents (9.2% vs 3.2%; p=0.04). Decision-making and prescription-writing errors comprised 33% and 67% of errors, respectively. CONCLUSIONS: The post-call state in surgery residents is associated with a significantly higher proportion of medication prescription errors in a hospital without a CPOE system. Decision-making and prescription-writing errors could potentially be addressed by additional educational interventions.

Assessment of fitness to perform using a validated self-test in obstetric and gynecological night shifts in the Netherlands.

BACKGROUND: The field of obstetrics and gynecology requires complex decision-making and skills because of unexpected high-risk situations. These skills are influenced by alertness, reaction time, and concentration. Night shifts result in sleep deprivation, which might impair these functions, although it is still unclear to what extent. OBJECTIVE: This study aimed to investigate whether a night shift routinely impairs the obstetrics and gynecology consultants' and residents' fitness to perform and whether this reaches a critical limit compared with relevant frames of reference. STUDY DESIGN: Residents (n=33) and consultants (n=46) in obstetrics and gynecology conducted multiple measurements (n=415) at precall, postcall, and noncall moments with the fitness to perform self-test. The self-test consists of an adaptive pursuit tracking task that is able to objectively measure alertness, reaction time, concentration, and hand-eye coordination and Visual Analog Scale tests to subjectively score alertness. The test is validated with a sociolegal reference of a 0.06% ethanol blood concentration (the peak level after 2 units of alcohol, the legal driving limit). This equals -1.37% on the objective score and -8.17 points on subjective alertness. Linear mixed models were used to analyze the difference within subjects over a night shift, integrating repeated measures over time. RESULTS: The overnight objective difference between postcall and precall measurements was -0.62 (P<.05) for residents and 0.28 (P=NS) for consultants, both not exceeding the sociolegal reference as a group. Objective impairment exceeded the reference for 31% of the residents and 28% of the consultants. Subjective alertness decreased in residents (-18.26; P<.001) and consultants (-10.85; P<.001), both exceeding the reference. No residents had to continue work postcall versus 7.8% of the consultants. None of the consultants that had to continue work were in an objective critically impaired state. CONCLUSION: This study provides insight and awareness of individual performance after night shifts with clear frames of reference. The performance of residents is negatively and significantly affected by night shifts; therefore, a scheduled day off after a night shift is justified. Consultants showed no overall impairment; however, a quarter did exceed the alcohol limit reference after their night shift. If not logistically feasible to schedule a protected day off after a night shift, our group recommends safe shift scheduling, including options to transfer care after a demanding night shift to prevent working in a compromised state.

Home-EEG assessment of possible compensatory mechanisms for sleep disruption in highly irregular shift workers - The ANCHOR study.

STUDY OBJECTIVES: While poor sleep quality has been related to increased risk of Alzheimer's disease, long-time shift workers (maritime pilots) did not manifest evidence of early Alzheimer's disease in a recent study. We explored two hypotheses of possible compensatory mechanisms for sleep disruption: Increased efficiency in generating deep sleep during workweeks (model 1) and rebound sleep during rest weeks (model 2). METHODS: We used data from ten male maritime pilots (mean age: 51.6±2.4 years) with a history of approximately 18 years of irregular shift work. Subjective sleep quality was assessed with the Pittsburgh Sleep Quality Index (PSQI). A single lead EEG-device was used to investigate sleep in the home/work environment, quantifying total sleep time (TST), deep sleep time (DST), and deep sleep time percentage (DST%). Using multilevel models, we studied the sleep architecture of maritime pilots over time, at the transition of a workweek to a rest week. RESULTS: Maritime pilots reported worse sleep quality in workweeks compared to rest weeks (PSQI = 8.2±2.2 vs. 3.9±2.0; p<0.001). Model 1 showed a trend towards an increase in DST% of 0.6% per day during the workweek (p = 0.08). Model 2 did not display an increase in DST% in the rest week (p = 0.87). CONCLUSIONS: Our findings indicated that increased efficiency in generating deep sleep during workweeks is a more likely compensatory mechanism for sleep disruption in the maritime pilot cohort than rebound sleep during rest weeks. Compensatory mechanisms for poor sleep quality might mitigate sleep disruption-related risk of developing Alzheimer's disease. These results should be used as a starting point for future studies including larger, more diverse populations of shift workers.

Night work and quality of life. A study on the health of nurses.

BACKGROUND: Job quality and evaluation of workers' health have both medical and social important implications. We studied health-related quality of life (HRQL) in nurses who perform their activity in night shifts. METHODS: A cross-sectional study was conducted between October and November 2014. Nurses who attended night shift in the Siena Teaching Hospital (Azienda Ospedaliera Universitaria Senese - AOUS) were sampled using EpiInfo software (confidence interval 95%) and investigated using the SF-36 Questionnaire. Our results were compared with the Italian general population (Apolone, 1997). A Descriptive analysis was conducted. Wilcoxon test, Pearson coefficient, t-test, Wilcoxon signed-rank test and logistic regression were used for the statistical investigation. RESULTS: 197 questionnaires were analyzed. Females were 71.7%; mean age was 39.2 years (DS 8.6); smokers were 37.8%. Males scores were higher than those of females in all dimensions of physical and mental health (p <0.05). The time taken to reach the place of work appeared to influence the dimension of General Health (coeff. -0.17); we found a worsening of 0.17 points of this dimension for every minute spent in travel. Men and nurses with more working years had a better score in Physical Pain dimension. AOUS nurses scored significantly (p <0.05) less compared with the correspondent Italian general population in General Health, Energy-fatigue, Social functioning, Physical functioning and Bodily pain. CONCLUSIONS: There is a significant relationship between night work and HRQL of nurses. The health profile of AOUS nurses' ranks below the values of the Italian general population in various dimensions.

Long working hours and depressive symptoms: moderating effects of gender, socioeconomic status, and job resources.

PURPOSE: Systematic reviews and meta-analyses have found inconsistent associations between working hours and depressive symptoms. The purpose of this study was to investigate the possible moderators of this association, using data from a large-scale cross-sectional survey. METHODS: A total of 16,136 Japanese employees (men 83.5%; women 16.5%) responded to a self-administered questionnaire inquiring about overtime working hours during the previous month and depressive symptoms (Center for Epidemiologic Studies Depression scale), as well as moderating factors including gender, age, marital status, socioeconomic status, commuting time, sleeping hours per day, job control and worksite social support (Job Content Questionnaire), neuroticism (Eysenck's Personality Questionnaire Revised), and social desirability (Social Desirability Scale) (response rate, 85%). We conducted sequential regression analyses to investigate the main effects and interaction effects of all moderating variables. RESULTS: The association between overtime working hours and depressive symptoms was significantly moderated by gender (interaction effect: ß = 0.03), age (ß = - 0.02), manager (ß = 0.03), sleeping hours (ß = - 0.02), job control (ß = - 0.03), and neuroticism (ß = 0.02). Among workers engaged in 80 + hours of overtime, higher depressive symptoms were reported by women, younger employees, non-managers, employees with low job control, low worksite social support, and high neuroticism. A significant main effect of long overtime working hours on depressive symptoms was also observed even after controlling for all independent variables (ß = 0.02). CONCLUSIONS: Long overtime working hours is associated with depressive symptoms. We also found significant heterogeneity in the association according to employee characteristics, which may explain the inconsistent findings in previous literature.

Association between working hours, work engagement, and work productivity in employees: A cross-sectional study of the Japanese Study of Health, Occupation, and Psychosocial Factors Relates Equity.

OBJECTIVES: The aims of the study were to investigate the association between working hours, work engagement, and work productivity, and to examine if work engagement moderates the influence of working hours on work productivity. METHODS: We used cross-sectional data from the Japanese occupational cohort survey, which involved 2093 employees in a manufacturing industry. Working hours were self-reported by the study participants. Work productivity was assessed with absolute presenteeism based on the scale of the validated Japanese version of World Health Organization Health and Work Performance Questionnaire (WHO-HPQ). Work engagement was assessed with the Nine-item Utrecht work Engagement Scale (UWES-9). Univariate and multivariable regression analyses were conducted to examine the association of working hours and work engagement with work productivity. We also carried out stratified multivariable regression analysis separately for those with high-work engagement and those with low-work engagement. RESULTS: Working >40 to 50 hours per week and >50 hours per week were significantly positively associated with work productivity in univariate analysis. However, the significant association no longer held after adjusting for work engagement. Work engagement was positively associated with work productivity even after controlling for potential confounders. Working hours were not significantly associated with work productivity among those with high-work engagement or among those with low-work engagement. CONCLUSIONS: Working hours did not have any significant associations with work productivity when taking work engagement into account. Work engagement did not moderate the influence of working hours on work productivity, though it attenuated the relationship between working hours and work productivity.

WHO/ILO work-related burden of disease and injury: Protocol for systematic reviews of exposure to long working hours and of the effect of exposure to long working hours on depression.

BACKGROUND: The World Health Organization (WHO) and the International Labour Organization (ILO) are developing a joint methodology for estimating the national and global work-related burden of disease and injury (WHO/ILO joint methodology), with contributions from a large network of experts. In this paper, we present the protocol for two systematic reviews of parameters for estimating the number of deaths and disability-adjusted life years from depression attributable to exposure to long working hours, to inform the development of the WHO/ILO joint methodology. OBJECTIVES: We aim to systematically review studies on occupational exposure to long working hours (Systematic Review 1) and systematically review and meta-analyse estimates of the effect of long working hours on depression (Systematic Review 2), applying the Navigation Guide systematic review methodology as an organizing framework, conducting both systematic reviews in tandem and in a harmonized way. DATA SOURCES: Separately for Systematic Reviews 1 and 2, we will search electronic academic databases for potentially relevant records from published and unpublished studies, including Medline, EMBASE, Web of Science, CISDOC and PsycINFO. We will also search electronic grey literature databases, Internet search engines and organizational websites; hand search reference list of previous systematic reviews and included study records; and consult additional experts. STUDY ELIGIBILITY AND CRITERIA: We will include working-age (≥15 years) participants in the formal and informal economy in any WHO and/or ILO Member State, but exclude child workers (<15 years) and unpaid domestic workers. For Systematic Review 1, we will include quantitative prevalence studies of relevant levels of occupational exposure to long working hours (i.e. 35-40, 41-48, 49-54 and ≥55 h/week) stratified by country, sex, age and industrial sector or occupation, in the years 2005-2018. For Systematic Review 2, we will include randomized controlled trials, cohort studies, case-control studies and other non-randomized intervention studies with an estimate of the relative effect of relevant level(s) of long working hours on the incidence of or mortality due to depression, compared with the theoretical minimum risk exposure level (i.e. 35-40 h/week). STUDY APPRAISAL AND SYNTHESIS METHODS: At least two review authors will independently screen titles and abstracts against the eligibility criteria at a first stage and full texts of potentially eligible records at a second stage, followed by extraction of data from qualifying studies. At least two review authors will assess risk of bias and the quality of evidence, using the most suited tools currently available. For Systematic Review 2, if feasible, we will combine relative risks using meta-analysis. We will report results using the guidelines for accurate and transparent health estimates reporting (GATHER) for Systematic Review 1 and the preferred reporting items for systematic reviews and meta-analyses guidelines (PRISMA) for Systematic Review 2. PROSPERO REGISTRATION NUMBER: CRD42018085729.

Working Time Society consensus statements: Evidence-based effects of shift work and non-standard working hours on workers, family and community.

Working time arrangements that require shift work or other non-standard working hours have significant potential to encroach on time that is highly valued for family, social and leisure activity. This can often result in workers experiencing poorer work-family or work-life balance. Based on an extensive literature search and expert knowledge, primary risk factors were identified including shift work; long, irregular and unpredictable working hours; and work on evenings and weekends (in combination and independent of shift work). On the other hand, flexibility, in the form of adequate worker control over work schedules, may be a protective factor. In addition, workers experiencing excessive work-life conflict are likely to reduce their working hours, reflecting a reciprocal relationship between working hours and work-life balance. Workers' families are also affected by shift work and non-standard working hours. Parents' shift work is associated with poorer emotional and developmental outcomes for their children, and to a greater likelihood of risky behavior in adolescence. Additionally, the risk of separation or divorce is increased, especially for parents working night shifts. Due to relationships such as those above, the consequences of shiftwork and non-standard working hours on family and social life are largely dependent on a complex interaction between specific work schedules, other aspects of work organization, and family and individual worker characteristics. This article provides an overview of current evidence regarding the relationships between working time arrangements and various social and family variables, and concludes with shift scheduling and intervention recommendations to improve work-life balance and social well-being.

Effects of work conditions on suicidal ideation among middle-aged adults in South Korea.

BACKGROUND: Korea has the highest rate of suicide in the world and has held this rank for the last decade. Suicide has risen especially sharply among 45- to 54-year-old Koreans; there were about 32.1 suicides per 100,000 individuals in 2015, and this contributed significantly to the rising suicide rate in Korea. Recently, adverse work conditions, including insecure employment and shift work, have been suggested as a suicide risk factor. However, little is known about the influence of insecure employment on suicidal ideation among middle-aged adults. Furthermore, prior research has examined the association between shift work and suicidal ideation only among individuals engaged in specific jobs, such as police work or firefighting, and those investigations have not focused on middle-aged adults. AIM: This study investigated the influence of employment status and shift work on suicidal ideation among middle-aged adults. METHODS: The sample comprised waged, middle-aged adult employees ( n = 2,364) aged 45-64 years who had participated in the cross-sectional Korea National Health and Nutrition Examination Survey 2015. Using multivariate logistic regression analyses, this study evaluated the associations of employment status and shift work with suicidal ideation among middle-aged adults. RESULTS: The major finding was that insecure employment status was independently associated with suicidal ideation in middle-aged adults (odds ratio (OR) = 2.50, 95% confidence interval (CI) = [1.27, 4.94]) and that shift work was significantly associated with suicidal ideation among middle-aged adults (OR = 2.30, 95% CI = [1.14, 4.66]). CONCLUSIONS: The findings of this study highlight the need for multidimensional interventions regarding suicide, especially for middle-aged adults engaged in insecure jobs and shift work. Multidimensional interventions, including early screening for suicidal thoughts during routine medical check-ups, readily available work-based counselling programmes and regular monitoring, are likely to be useful.

Shift-work nurses' work environments and health-promoting behaviours in relation to sleep disturbance: A cross-sectional secondary data analysis.

AIMS AND OBJECTIVES: To examine the association of nursing work environments and health-promoting behaviours with shift-work nurses' sleep disturbance. BACKGROUND: Shift-work nurses reportedly have sleep problems, which affect their sleep quality and quantity. Given the high risk of developing performance decrements and medication errors in sleep-disturbed nurses, factors related to sleep disturbance among shift-work nurses should be investigated. DESIGN: A cross-sectional secondary data analysis. METHODS: Our study analysed data from 339 nurses who had been involved in rotating shift work including night shifts for more than 6 months. To examine associations of nursing work environments and health-promoting behaviours with sleep disturbance, multiple linear regression models were generated. This study is reported in accordance with the STrengthening the Reporting of OBservational studies in Epidemiology guideline. RESULTS: Nurses with more collegial relations with physicians were significantly less likely to have high levels of sleep disturbance (B = -4.01, p = 0.04). Those with higher levels of sleep disturbance were significantly more likely to report less stress management (B = -9.56, p < 0.01) and higher health responsibility (B = 9.30, p < 0.01). CONCLUSIONS: To alleviate shift-work nurses' sleep disturbance, organisational supports for collaborative relations with physician and increased healthcare accessibility are needed. Individual nurses should develop healthy lifestyles to reduce occupational stress and alleviate sleep disorders. RELEVANCE TO CLINICAL PRACTICE: To improve shift-work nurses' sleep, collegial relations with physicians and healthy lifestyles should be promoted.

Health behaviours of Australian fly-in, fly-out workers and partners during on-shift and off-shift days: an ecological momentary assessment study.

OBJECTIVES: Fly-in, fly-out (FIFO) work involves long commutes, living on-site for consecutive days and returning home between shifts. This unique type of work requires constant transitioning between the roles and routines of on-shift versus off-shift days. This study aims to examine health behaviour patterns of FIFO workers and FIFO partners during on-shift and off-shift time frames. DESIGN: This study used ecological momentary assessment and multilevel modelling to examine daily health behaviours. SETTING: FIFO workers and FIFO partners from across Australia responded to daily online surveys for up to 7 days of on-shift and up to 7 days of off-shift time frames. PARTICIPANTS: Participants included 64 FIFO workers and 42 FIFO worker partners. RESULTS: Workers and partners reported poorer sleep and nutrition quality for on-shift compared with off-shift days. Both workers and partners exercised less, smoked more cigarettes, took more physical health medication and drank less alcohol during on-shift compared with off-shift days. CONCLUSIONS: FIFO organisations should consider infrastructure changes and support services to enhance opportunities for quality sleep and nutrition, sufficient exercise, moderate alcohol consumption and cigarette cessation for workers on-site and their partners at home.

Clouds of different colors: A prospective look at head and neck surgical resident call experience.

Graduate medical education programs typically set up call under the assumption that residents will have similar experiences. The terms black cloud and white cloud have frequently been used to describe residents with more difficult (black) or less difficult (white) call experiences. This study followed residents in the department of head and neck surgery during call to determine whether certain residents have a significantly different call experience than the norm. It is a prospective observational study conducted over 16 months in a tertiary care center with a resident training program in otolaryngology. Resident call data on total pages, consults, and operative interventions were examined, as well as subjective survey data about sleep and perceived difficulty of resident call. Analysis showed no significant difference in call activity (pages, consults, operative interventions) among residents. However, data from the resident call surveys revealed perceived disparities in call difficulty that were significant. Two residents were clearly labeled as black clouds compared to the rest. These residents did not have the highest average number of pages, consults, or operative interventions. This study suggests that factors affecting call perception are outside the objective, absolute workload. These results may be used to improve resident education on sleep training and nighttime patient management in the field of otolaryngology and may influence otolaryngology residency programs.

Examining self-reported and biological stress and near misses among Emergency Medicine residents: a single-centre cross-sectional assessment in the USA.

OBJECTIVES: To examine the relationship between perceived and biological stress and near misses among Emergency Medicine residents. DESIGN: Self-rated stress and stress biomarkers were assessed in residents in Emergency Medicine before and after a day shift. The supervising physicians and residents reported numbers of near misses. SETTING: The study took place in the Emergency Department of a large trauma 1 centre, located in Detroit, USA. PARTICIPANTS: Residents in Emergency Medicine volunteered to participate. The sample consisted of 32 residents, with complete data on 28 subjects. Residents' supervising physicians assessed the clinical performance of each resident. PRIMARY AND SECONDARY OUTCOME MEASURES: Participants' preshift and postshift stress, biological stress (salivary cortisol, plasma interleukin-6, tumour necrosis factor-alpha (TNF-α) and high-sensitivity C-reactive protein), residents' and supervisors' reports of near misses, number of critically ill and patients with trauma seen during the shift. RESULTS: Residents' self-reported stress increased from an average preshift level of 2.79 of 10 (SD 1.81) to a postshift level of 5.82 (2.13) (p<0.001). Residents cared for an average of 2.32 (1.52) critically ill patients and 0.68 (1.06) patients with trauma. Residents reported a total of 7 near misses, compared with 11 reported by the supervising physicians. After controlling for baseline work-related exhaustion, residents that cared for more patients with trauma and had higher levels of TNF-α reported a higher frequency of near misses (R2=0.72; p=0.001). Residents' preshift ratings of how stressful they expected the shift to be were related to the supervising physicians' ratings of residents' near misses during the shift. CONCLUSION: Residents' own ratings of near misses were associated with residents' TNF-α, a biomarker of systemic inflammation and the number of patients with trauma seen during the shift. In contrast, supervisor reports on residents' near misses were related only to the residents' preshift expectations of how stressful the shift would be.

The relationship between job satisfaction, work stress, work-family conflict, and turnover intention among physicians in Guangdong, China: a cross-sectional study.

OBJECTIVE: To investigate the relationship between job satisfaction, work stress, work-family conflict and turnover intention, and explore factors associated with turnover intention, among physicians in Guangdong Province, China. METHODS: From August to October 2013, physicians completed questionnaires and scales with regard to their job satisfaction, work stress, work-family conflict, and turnover intention. Binary logistic regression and structural equation modelling (SEM) were used in data analysis. RESULTS: A total of 3963 physicians were approached, with 3563 completing the questionnaire. The mean score of the overall perception of turnover intention of physicians who worked in Guangdong was 2.71 on a scale ranging from 1 to 6. Hours worked per week, working in an urban/rural area, type of institution, and age significantly impacted on turnover intention. Turnover intention was directly and negatively related to job satisfaction, and it was directly, indirectly and positively related to work stress and work-family conflict. CONCLUSION: Job satisfaction, work stress, work-family conflict, hours worked per week, working in an urban/rural area, types of institution and age are influencing factors of turnover intention. Reducing working hours, raising salary, providing more opportunities for career development and training, supporting and encouraging physicians by senior managers could potentially contribute to the reduction in turnover intention.

Overwork-related disorders in Japan: recent trends and development of a national policy to promote preventive measures.

Overwork-related disorders, such as cerebrovascular/cardiovascular diseases (CCVD) and mental disorders due to overwork, are a major occupational and public health issue worldwide, particularly in East Asian countries. This report discusses the recent trend of overwork-related disorders in Japan from the perspective of workers' compensated occupational diseases, as well as the development of a national policy for preventive measures against overwork-related disorders in Japan. Recently, the number of claimed and compensated cases of occupational mental disorders has increased substantially, particularly among young workers, as compared to those of occupational CCVD. In response to these situations and action from society, the Japanese Government passed the "Act on Promotion of Preventive Measures against Karoshi and Other Overwork-Related Health Disorders" in June 2014 to develop a national initiative towards the prevention of overwork-related disorders. Changes in the trend of overwork-related disorders in Japan under a legal foundation and an initiative by the central government should be closely monitored so that other countries can benefit from the experiences.

Determinants of seafarers' fatigue: a systematic review and quality assessment.

PURPOSE: Fatigue jeopardizes seafarer's health and safety. Thus, knowledge on determinants of fatigue is of great importance to facilitate its prevention. However, a systematic analysis and quality assessment of all empirical evidence specifically for fatigue are still lacking. The aim of the present article was therefore to systematically detect, analyze and assess the quality of this evidence. METHODS: Systematic searches in ten databases were performed. Searches considered articles published in scholarly journals from 1980 to April 15, 2016. Nineteen out of 98 eligible studies were included in the review. The main reason for exclusion was fatigue not being the outcome variable. RESULTS: Most evidence was available for work time-related factors suggesting that working nights was most fatiguing, that fatigue levels were higher toward the end of watch or shift, and that the 6-h on-6-h off watch system was the most fatiguing. Specific work demands and particularly the psychosocial work environment have received little attention, but preliminary evidence suggests that stress may be an important factor. A majority of 12 studies were evaluated as potentially having a high risk of bias. CONCLUSIONS: Realistic countermeasures ought to be established, e.g., in terms of shared or split night shifts. As internal as well as external validity of many study findings was limited, the range of factors investigated was insufficient and few studies investigated more complex interactions between different factors, knowledge derived from studies of high methodological quality investigating different factors, including psychosocial work environments, are needed to support future preventive programs.