Effects of a work schedule with abated quick returns on insomnia, sleepiness and work-related fatigue: Results from a large-scale cluster randomized controlled trial.

STUDY OBJECTIVES: To investigate the effect of a work schedule with abated quick returns (i.e., >11 hours between two shifts) on insomnia, daytime sleepiness, and work-related fatigue compared to a shift schedule maintaining the usual number of quick returns. METHODS: A two-armed cluster randomized controlled trial including 66 units was conducted at a university hospital in Norway. Units with healthcare workers on rotating shift schedules were randomly assigned to a shift schedule with abated quick returns (intervention) or to continue with a schedule including quick returns as usual (control) for six months. Questionnaires assessed symptoms of insomnia (Bergen Insomnia Scale), daytime sleepiness (Epworth Sleepiness Scale), and work-related fatigue (Revised Swedish Occupational Fatigue Inventory) at baseline and towards the end of the intervention. Data was analyzed using multilevel linear mixed-effects models, and Cohen's d was used to calculate the effect size between groups. RESULTS: Overall, 1314 healthcare workers (85.2% female) completed the baseline questionnaire (response rate 49.1%), and 552 completed the follow-up questionnaire. The intervention reduced quick returns from an average of 13.2 (SD=8.7) to 6.7 (SD=6.0), while the control group's average remained relatively unchanged from 13.2 (SD=8.7) to 12.0 (SD=9.3). Results showed a small improvement in symptoms of insomnia (BIS; d=-0.13, p=0.022) and daytime sleepiness (ESS; d=-0.14, p=0.013) in favor of the intervention. No effects were observed on work-related fatigue. CONCLUSIONS: Reducing the number of quick returns resulted in improvements in insomnia and daytime sleepiness. The findings highlight the importance of sufficient rest time in the work schedule of healthcare workers.

Moral decision-making at night and the impact of night work with blue-enriched white light or warm white light: a counterbalanced crossover study.

BACKGROUND: Cognitive function, including moral decision-making abilities, can be impaired by sleep loss. Blue-enriched light interventions have been shown to ameliorate cognitive impairment during night work. This study investigated whether the quality of moral decision-making during simulated night work differed for night work in blue-enriched white light, compared to warm white light. METHODS: Using a counterbalanced crossover design, three consecutive night shifts were performed in blue-enriched white light (7000 K) and warm white light (2500 K) provided by ceiling-mounted LED luminaires (photopic illuminance: ∼200 lx). At 03:30 h on the second shift (i.e. twice) and at daytime (rested), the Defining Issues Test-2, assessing the activation of cognitive schemas depicting different levels of cognitive moral development, was administered. Data from 30 (10 males, average age 23.3 ± 2.9 years) participants were analysed using linear mixed-effects models. RESULTS: Activation of the post-conventional schema (P-score), that is, the most mature moral level, was significantly lower for night work in warm white light (EMM; estimated marginal mean = 44.3, 95% CI = 38.9-49.6; pholm=.007), but not blue-enriched white light (EMM = 47.5, 95% CI = 42.2-52.8), compared to daytime (EMM = 51.2, 95% CI = 45.9-56.5). Also, the P-score was reduced for night work overall (EMM = 45.9, 95% CI = 41.1-50.8; p=.008), that is, irrespective of light condition, compared to daytime. Neither activation of the maintaining norms schema (MN-score), that is, moderately developed moral level, nor activation of the personal interest schema (i.e. the lowest moral level) differed significantly between light conditions. The MN-score was however increased for night work overall (EMM = 26.8, 95% CI = 23.1-30.5; p=.033) compared to daytime (EMM = 23.1, 95% CI = 18.9-27.2). CONCLUSION: The results indicate that moral decisions during simulated night work in warm white light, but not blue-enriched white light, become less mature and principle-oriented, and more rule-based compared to daytime, hence blue-enriched white light may function as a moderator. Further studies are needed, and the findings should be tentatively considered.Trial registration: ClinicalTrials.gov (ID: NCT03203538) Registered: 26/06/2017; https://clinicaltrials.gov/study/NCT03203538.

The quality of moral decision-making, seen as the activation of cognitive schemas depicting different levels of moral development, was reduced during simulated night work in warm white light, but not blue-enriched light, compared to daytime.The quality of moral decision-making sems to be reduced during simulated night work, compared to daytime.More studies assessing the impact of night work and light interventions on the quality of moral decision-making are needed to validate these tentative findings.

Simulated quick returns in a laboratory context and effects on sleep and pre-sleep arousal between shifts: a crossover controlled trial.

This trial presents a laboratory model investigating the effect of quick returns (QRs, <11 h time off between shifts) on sleep and pre-sleep arousal. Using a crossover design, 63 participants worked a simulated QR condition (8 h time off between consecutive evening- and day shifts) and a day-day (DD) condition (16 h time off between consecutive day shifts). Participants slept at home and sleep was measured using a sleep diary and sleep radar. Compared to the DD condition, the QR condition reduced subjective and objective total sleep time by approximately one hour (both p < .001), reduced time in light- (p < .001), deep- (p = .004), rapid eye movement (REM, p < .001), percentage of REM sleep (p = .023), and subjective sleep quality (p < .001). Remaining sleep parameters and subjective pre-sleep arousal showed no differences between conditions. Results corroborate previous field studies, validating the QR model and indicating causal effects of short rest between shifts on common sleep parameters and sleep architecture.

This trial proposes a laboratory model to investigate the consequences of quick returns (QRs, <11h time off between shifts) on subjective/objective sleep and pre-sleep arousal. QRs reduced total sleep time, light-, deep-, REM sleep, whereas pre-sleep arousal was unaffected. Results emphasise the importance of ensuring sufficient rest time between shifts.Abbreviation: QR: Quick return; DD: Day-day; NREM: Non-rapid eye movement; REM: Rapid eye movement; PSG: Polysomnography; TIB: Time in bed; SOL: Sleep onset latency; WASO: Wake after sleep onset; TST: Total sleep time; EMA: Early morning awakening; PSAS: Pre-Sleep Arousal Scale; MEQ: Morning-Evening Questionnaire; LMM: Linear mixed model; EMM: Estimated marginal mean; SD: Standard deviation; SE: Standard error; d: Cohens' d; h: hours; m: minutes.

The prevalence of orthorexia in exercising populations: a systematic review and meta-analysis.

AIM: Orthorexia Nervosa (ON) describes a pathological obsession with proper and high-quality nutrition that is necessary to research further in order to elucidate its prevalence and correlates which may bear implications for prevention and treatment. The aim of this study was to review studies that report the prevalence of ON in people who exercise, calculate an overall prevalence through a random-effects meta-analysis approach and investigate the association of ON prevalence using a random-effects meta-regression. In addition, a sub-group-analysis based on ON-instruments and a sensitivity analysis excluding students samples, were conducted. METHOD: Systematic searches were conducted in the following online databases: PubMed, Embase, Web of Science, PsychInfo, CINAHL, Google Scholar and OpenNet. The following search terms were used: Orthore* AND (prevalenc* OR incidenc* OR frequen* OR cut-off OR epidem*). A total of 613 unique hits were reviewed by two blinded authors, and 24 studies were coded and assessed for risk of bias (Holy et.al). The meta-regression included three independent variables (sex, type of sport, and sample size). RESULTS: The overall prevalence of ON in the exercising population was 55.3% (95% CI 43.2-66.8). Cochran's Q was 11,436.38 (df = 23, p < 0.0000), and the I2 was 98.4%, indicating high heterogeneity across studies. The sensitivity showed an overall prevalence of 51.3% (95% CI 51.3-70.0). There was a significant difference in prevalence estimates based on the instruments used (Qbet = 33.6, df = 2, p < 0.01). DISCUSSION: The overall prevalence of ON in exercising populations was very high. The between-study disparity was large and was partly explained by the ON-instrument administered. One fourth of the studies had a moderate risk of bias. The majority of the studies did not specify relevant demographic information about the sample, and information about the type of sport was frequently missing.

Orthorexia Nervosa (ON) describes a pathological obsession with proper and high quality nutrition that is characterized by a restrictive diet, ritualized patterns of eating, and rigid avoidance of foods believed to be unhealthy or impure. This obsession is found among sports athletes in some studies, and there is an assumed link between ON and exercise in general. In this study, the term exercise is defined as any activity requiring physical effort, carried out to sustain or improve health and fitness. In this systematic review and meta-analysis, we examined the overall prevalence of ON in the exercising population. Searching in scientific databases resulted in 613 articles, of which 24 met the rigorous inclusion criteria. The overall prevalence of ON in the general exercising population was 55.3%. The prevalence was thought to be predictable by sex, type of sport, and sample size, but no significant associations were found. This may be due to poor study quality and a lack of demographic information on the participants in some of the included studies. Other predictors worth investigating might be age, student status, status as vegetarian/vegan, psychiatric comorbidity, and intensity/frequency of exercise. This knowledge may bear implications for the prevention and right treatment for people at risk of developing ON.

The impact of follower leadership position on transformational leadership as moderator of the association between work-related ambiguity and job satisfaction.

This two-part study examined if the buffering effect of transformational leadership on the association between work-related ambiguity and job satisfaction is contingent upon whether a follower holds a formal leadership position him/herself. Data from two separate surveys were employed: Study 1: A sample of 845 respondents from Belgium. Study 2: A national probability sample of 1,608 Norwegian employees. Study 1 showed that task ambiguity had a significant negative relation with job satisfaction, but that transformational leadership did only buffer the association between task ambiguity and job satisfaction among employees holding a formal position as a supervisor or manager. Study 2 extended Study 1 by adjusting for age and job tenure of subordinates as a confounding variable. Study 2 confirmed that transformational leadership had a significantly stronger impact on the observed association between role ambiguity and job satisfaction among respondents holding a supervisor or manager position. In conclusion, when considering job satisfaction as an outcome of work-related ambiguity, transformational leadership is mainly beneficial for followers holding a formal supervisor or manager position themselves. Our findings thereby question assumptions about the general effectiveness of transformational leadership.

Crisis leadership in COVID-19: A qualitative study of Norwegian business leaders.

Background: On March 11, 2020, the World Health Organization declared the novel coronavirus outbreak a global pandemic. The crisis that follows presented significant adverse challenges for organizations and business leaders around the world. The present study aims to explore how the extreme context of the COVID-19 influenced crisis leadership, with emphasis on coping and adaptive approaches, in Norwegian leaders during the early stage of the pandemic. Materials and methods: A group of 11 Norwegian business leaders from different private sector companies were subject to an in depth, semi structured interview after the first 9 months of COVID-19. A sensemaking perspective and the Cognitive Activation Theory of Stress (CATS) were used to interpret the results. Results: The pandemic called for crisis leadership and a rapid adaptation to a radically changed situation. Restructuring of organizational processes and introduction of new routines were followed by support and caring for their employees during the first wave of the pandemic. All the leaders coped well with the situation, and some were excited over the opportunity to make a difference in this demanding and stressful situation. Many emphasized that the pandemic was an external threat, resulting in an acceptance of the situation, more transparency, collaboration, and generosity within the organization. Especially the willingness to change was challenged in a positive way. A more blurred line between office and home, and absence of social activities were mentioned as negative outcomes.

Performance in youth track and field is associated with birth quartile. A register-based study among athletes in Norway from 10 years to senior level.

INTRODUCTION: Earlier studies have demonstrated that the oldest in a competition class are more likely to succeed than the youngest, a phenomenon called relative age effect (RAE). Track and field give us an opportunity to investigate the advantage of being born early in the year based upon actual performance, since objective criteria are the performance indicators. Hence, the aim of the present study was to investigate the occurrence of RAE in Norwegian track and field athletes in events where physical capacity is important for success. METHODS: All individual season best results from the register of The Norwegian Athletics Federation (n = 28 999) obtained in all competition classes from the age of 10 years to senior in both sexes on 60m and 600m from 2011 to 2020 were downloaded. One-way ANOVA and LSD post hoc analyses were used to analyze performance differences according to birth quartiles between athletes. Further, odds ratios (OR) were used to calculate the odds of being among the top-100 for athletes for those born in the first quartile of the year compared to the last. RESULTS: The RAE was present in several of the competition classes in sprint compared to middle-distance running, and in more male than female competition classes. Overall, the OR of being among the top-100 in one of the competition classes on 60m sprint when born in first quartile compared to last quartile was 2.88 [2.30-3.62] for males and 1.54 [1.26-1.89] for females. CONCLUSION: Being born early in the year in events with high demand for specific physical capacities is an advantage in both sexes in most of the youngest competition classes. In males, the advantage of being born early in the year lasted longer in sprint than in middle-distance running, indicating that puberty affects performance in sprint and middle-distance running differently.

Healing the wounds of workplace bullying: Evaluating mental health and workplace participation among victims seeking treatment for common mental disorders.

BACKGROUND: Victims of workplace bullying represent a group characterised by severe negative health complaints at risk of losing their foothold in working life. To date, very few studies have investigated the effect of psychological treatment of the health-related problems often facing victims of bullying. OBJECTIVE: The aim was to investigate if victims of workplace bullying suffering from common mental disorders (CMD) benefit from clinical treatment for their mental health problems at an outpatient clinic treating patients using Metacognitive or Cognitive Behavioural Therapy with work-focus. Criteria were symptom reduction and change in workplace participation. Comparisons were made between the victims of workplace bullying with CMD, a wait-list control group consisting of patients who had also been exposed to bullying yet now awaiting treatment, and other patients not exposed to bullying. METHODS: The sample comprised of 405 patients from an outpatient clinic in Norway. The study used a naturalistic observational design and data was collected pre-treatment and post-treatment. RESULTS: The results showed the treatment to be effective in symptom reduction for victims of bullying to a similar degree as patients otherwise not exposed to bullying. Even more, victims receiving treatment had a larger improvement compared to the wait-list control group (p < 0.001). Yet, among patients on sick leave pre-treatment, fewer victims of bullying were fully working by the end of treatment compared to the patients not exposed to workplace bullying. CONCLUSION: The findings provide ground for optimism for this treatment as an efficient way of dealing with the aftermath of workplace bullying.

Changes in the Work Schedule of Nurses Related to the COVID-19 Pandemic and Its Relationship with Sleep and Turnover Intention.

Background: This study aimed to investigate whether different types of changes in the work schedule of nurses working rotating shifts during the COVID-19 pandemic were associated with sleep duration, sleep quality, and turnover intention. Methods: Cross-sectional questionnaire data from 694 nurses participating in the SUrvey of Shift work, Sleep and Health (SUSSH) were collected between the first and the second wave of the COVID-19 pandemic in Norway. A total of 89.9% were female, and mean age was 44.6 years (SD = 8.6 years). Changes in the shift work schedule related to the pandemic comprised reports of more long workdays (>8 h), less days off between work periods, more night shifts, more quick returns (i.e., 11 h or less between two consecutive shifts), more day shifts, and more evening shifts compared to no change in the respective shift characteristics. Change in sleep duration, sleep quality, and turnover intention as well as demographics were also assessed. Logistic regression analyses were performed to investigate whether changes in the specific work schedules were associated with sleep duration, sleep quality, and turnover intention, controlling for sex, age, cohabitation, children living in household, percentage of full time equivalent and other changes in the work schedule. Results: A total of 17% reported experiencing one or more changes in their work schedule during the pandemic. Experiencing any change in the work schedule predicted worse sleep quality (OR = 2.68, p < 0.001), reduced sleep duration (OR = 4.56, p < 0.001), and higher turnover intention (OR = 1.96, p = 0.006) compared to experiencing no change in work schedule. Among the specific changes in work schedules, experiencing an increase in quick returns had the highest odds ratio for worse sleep quality (OR = 10.34, p = 0.007) and higher turnover intention (OR = 8.49, p = 0.014) compared to those who reported no change in quick returns. Nurses experiencing an increase in long workdays were more likely to report higher turnover intention (OR = 4.37, p = 0.003) compared to those experiencing no change in long workdays. Conclusions: Change in work schedule related to the pandemic was associated with worse sleep quality, reduced sleep duration, and higher turnover intention. Increase in quick returns emerged as especially problematic in terms of sleep quality and turnover intention, along with long workdays, which were associated with higher turnover intention.

Sleep and work functioning in nurses undertaking inpatient shifts in a blue-depleted light environment.

BACKGROUND: Blue-depleted light environments (BDLEs) may result in beneficial health outcomes for hospital inpatients in some cases. However, less is known about the effects on hospital staff working shifts. This study aimed to explore the effects of a BDLE compared with a standard hospital light environment (STLE) in a naturalistic setting on nurses' functioning during shifts and sleep patterns between shifts. METHODS: Twenty-five nurses recruited from St. Olavs Hospital in Trondheim, Norway, completed 14 days of actigraphy recordings and self-reported assessments of sleep (e.g., total sleep time/sleep efficiency) and functioning while working shifts (e.g., mood, stress levels/caffeine use) in two different light environments. Additionally, participants were asked to complete several scales and questionnaires to assess the symptoms of medical conditions and mental health conditions and the side effects associated with each light environment. RESULTS: A multilevel fixed-effects regression model showed a within-subject increase in subjective sleepiness (by 17%) during evening shifts in the BDLE compared with the STLE (p = .034; Cohen's d = 0.49) and an 0.2 increase in number of caffeinated beverages during nightshifts in the STLE compared with the BDLE (p = .027; Cohen's d = 0.37). There were no significant differences on any sleep measures (either based on sleep diary data or actigraphy recordings) nor on self-reported levels of stress or mood across the two conditions. Exploratory between-group analyses of questionnaire data showed that there were no significant differences except that nurses working in the BDLE reported perceiving the lighting as warmer (p = .009) and more relaxing (p = .023) than nurses working in the STLE. CONCLUSIONS: Overall, there was little evidence that the change in the light environment had any negative impact on nurses' sleep and function, despite some indication of increased evening sleepiness in the BDLE. We recommend further investigations on this topic before BDLEs are implemented as standard solutions in healthcare institutions and propose specific suggestions for designing future large-scale trials and cohort studies. TRIAL REGISTRATION: The study was registered before data collection was completed on the ISRCTN website ( ISRCTN21603406 ).

Protocol for a systematic review and meta-analysis on the associations between shift work and sickness absence.

BACKGROUND: Shift work, i.e., non-standard work hours, has been associated with both short- and long-term sickness absence. However, findings are inconsistent and inconclusive. Thus far, no comprehensive meta-analytic synthesis on the relationship between shift work and sickness absence has been published. The aims of the planned systematic review and meta-analysis are (1) to establish whether shift work is associated with sickness absence, (2) to determine if specific shift work characteristics relate to sickness absence (e.g., length and frequency of spells), and (3) to identify moderating factors affecting the relationship between shift work and sickness absence. METHODS: Eligible studies will be identified using a predefined search strategy in several electronic databases (MEDLINE, Web of Science, PsychInfo, EMBASE, and ProQuest) and comprise peer-reviewed papers reporting original empirical findings on the association between shift work and sickness absence. Mainly observational studies with cross-sectional, prospective, or retrospective research design and case-control studies will be included. Risk of bias will be assessed using an adapted checklist previously employed to evaluate studies on sickness absence. To carry out the meta-analytic synthesis, a random effects meta-analysis will be conducted using the Comprehensive Meta-Analysis software. The review and meta-analysis will be reported according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Heterogeneity will be evaluated by Cochran's Q test and the I2 statistics. DISCUSSION: The review and meta-analysis will be the first to conduct a meta-analytic synthesis of the evidence on the association between exposure to shift work and sickness absence, as well as identify relevant moderators affecting the relationship between shift work and sickness absence. Aggregation of the existing evidence will improve the knowledge on the association between shift work and sickness absence. Such knowledge can be used to guide scheduling of shift work to promote work schedules that are less detrimental to health and contribute to reduced sickness absence and higher work- and leisure-time productivity. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42022301200.

The association between shift work disorder and turnover intention among nurses.

BACKGROUND: Shift work disorder (SWD) is highly prevalent among shift-working nurses and has multiple negative health-related effects. There is a dearth of insight into career-related decisions made by nurses suffering from SWD, for instance in terms of their intention to quit work (turnover intention). In this study, we aimed to investigate the association between SWD and turnover intention among nurses, and the individual and work-related correlates of turnover intention. METHOD: Data were derived from the ongoing longitudinal cohort study "SUrvey of Shift work, Sleep and Health (SUSSH)" among Norwegian nurses. An annual survey was initiated in 2008/2009 (N = 2965). The present study used data collected in year 2015 (wave 7) and 2016 (wave 8). Nurses were included if: 1) they were working as nurses in both 2015 and 2016, and 2) had completed a three-item scale adapted from the Michigan Organizational Assessment Questionnaire assessing turnover intention (in wave 8), and 3) did not only work day-shifts. SWD was measured in wave 7 with three questions based on the minimal criteria from the third edition of the International Classification of Sleep Disorders. Job demands, decision latitude, and social support at the workplace were measured with subscales of the Swedish Demand-Control-Support Questionnaire. RESULTS: Eight Hundred eighty-nine nurses were included. The results from the hierarchical linear regression showed that SWD predicted turnover intention one year later, i.e. from 2015 to 2016 (F1,835 = 6.00, p < 0.05; ß = 0.084, p = 0.015). The findings remained significant when controlling for age, sex, organizational tenure, number of nights worked, shift work schedule and workplace social support, job demands and decision latitude. CONCLUSION: This study showed that SWD is associated with turnover intention, even when controlling for individual and work-related variables.

Health-promoting work schedules: protocol for a large-scale cluster randomised controlled trial on the effects of a work schedule without quick returns on sickness absence among healthcare workers.

INTRODUCTION: In shift work, quick returns refer to transitions between two shifts with less than 11 hours available rest time. Twenty-three per cent of employees in European countries reported having quick returns. Quick returns are related to short sleep duration, fatigue, sleepiness, work-related accidents and sickness absence. The present study is the first randomised controlled trial (RCT) to investigate the effect of a work schedule without quick returns for 6 months, compared with a work schedule that maintains quick returns during the same time frame. METHODS AND ANALYSIS: A parallel-group cluster RCT in a target sample of more than 4000 healthcare workers at Haukeland University Hospital in Norway will be conducted. More than 70 hospital units will be assessed for eligibility and randomised to a work schedule without quick returns for 6 months or continue with a schedule that maintains quick returns. The primary outcome is objective records of sickness absence; secondary outcomes are questionnaire data (n≈4000 invited) on sleep and functioning, physical and psychological health, work-related accidents and turnover intention. For a subsample, sleep diaries and objective sleep registrations with radar technology (n≈ 50) will be collected. ETHICS AND DISSEMINATION: The study protocol was approved by the Regional Committee for Medical and Health Research Ethics in Western Norway (2020/200386). Findings from the trial will be disseminated in peer-reviewed journals and presented at national and international conferences. Exploratory analyses of potential mediators and moderators will be reported. User-friendly outputs will be disseminated to relevant stakeholders, unions and other relevant societal groups. TRIAL REGISTRATION NUMBER: NCT04693182.

Sleep and Sleepiness Measured by Diaries and Actigraphy among Norwegian and Austrian Helicopter Emergency Medical Service (HEMS) Pilots.

The study examined sleep and sleepiness among shift working Helicopter Emergency Medical Service pilots from Norway (Norwegian Air Ambulance; NAA) and Austria (Christophorus Flugrettungverein; CFV). Both pilot groups (N = 47) worked seven consecutive 24 h shifts. Sleep was assessed by diaries and actigraphy while sleepiness was assessed by the Karolinska Sleepiness Scale, all administered throughout the workweek. The results indicated that all pilots had later bedtime (p < 0.05) and wake-up time (p < 0.01) as they approached the workweek end, but no change during the workweek was evident regarding wake after sleep onset, time in bed, total sleep time, or sleep efficiency. The NAA pilots had later bedtime (p < 0.001) and wake-up time (p < 0.001), spent more time awake after sleep onset (p < 0.001), more time in bed (p < 0.001), slept longer (p < 0.01), and had lower sleep efficiency (p < 0.001) compared with the CFV pilots. The sleepiness levels of all pilots were slightly elevated on the first workday but lower on the following workdays (day 2p < 0.001, day 3p < 0.05). For both pilot groups, no major change in sleep or sleepiness parameters throughout the workweek was detected. The NAA pilots reported somewhat more disturbed sleep but obtained more sleep compared with the CFV pilots.

Bright light exposure during simulated night work improves cognitive flexibility.

Night work leads to sleepiness and reduced vigilant attention during work hours, and bright light interventions may reduce such effects. It is also known that total sleep deprivation impairs cognitive flexibility as measured by reversal learning tasks. Whether night work impairs reversal learning task performance or if bright light can mitigate reversal learning deficits during night work is unclear. In this counterbalanced crossover study (ClinicaTrials.gov Identifier NCT03203538), young healthy individuals completed a reversal learning task twice during each of three consecutive simulated night shifts (23:00-07:00 h). The night shifts were performed in a laboratory under a full-spectrum (4000 K) bright light (~900 lx) and a standard light (~90 lx) condition. Reversal learning task performance was reduced towards the end of the night shifts (04:50 h), compared to the first part of the night shifts (00:20 h) in both light conditions. However, with bright light, the reversal learning task performance improved towards the end of the night shifts, compared to standard light. The study shows that bright light may mitigate performance deficits on a reversal learning task during night work and implies that bright light interventions during night work may be beneficial not only for vigilant attention but also for cognitive flexibility.

Stability and Change of the Personality Traits Languidity and Flexibility in a Sample of Nurses: A 7-8 Years Follow-Up Study.

The traits languidity (tendency to become tired/sleepy upon losing sleep) and flexibility (ability to sleep and work at odd times) have been implicated in shift work tolerance. However, there is a dearth of knowledge about their temporal stability. The aim of the present study was to explore these traits during a long follow-up (FU) period and identify factors related to potential changes in trait scores over time. In all, 1,652 nurses completed the Circadian Type Inventory-revised (CTI-r), which measures languidity and flexibility, at both 2008/2009 (baseline, BL) and again in 2016 (FU). The latent scores of these two constructs at BL, in addition to age, sex, childcare responsibility, marital status, night work status, and insomnia status, were regressed on the corresponding latent scores at follow-up using a structural equation modeling (SEM) approach. Stability was found for both languidity (rho = 0.59) and flexibility (rho = 0.58). Both composite scores declined significantly from baseline (20.62 and 12.48) to follow-up (19.96 and 11.77). Languidity at baseline was positively associated with languidity at follow-up (ß = 0.89, p < 0.009). Undertaking childcare responsibility between baseline and follow-up was inversely related to languidity at follow-up (ß = -0.09, p < 0.05). Starting night work was positively related to languidity at follow-up (ß = 0.06, p < 0.05). Developing insomnia between baseline and follow-up (ß = 0.15, p < 0.05) was positively, whereas remitting from insomnia during the same period was negatively (ß = -0.11, p < 0.01) associated with languidity at follow-up. Flexibility at baseline was positively associated with flexibility at follow-up (ß = 0.64, p < 0.05). Having childcare responsibility at baseline, but not at follow-up was inversely related to flexibility at follow-up (ß = -0.05 p < 0.05). Becoming cohabitant with a partner between baseline and follow-up (ß = -0.07, p < 0.05) was negatively associated with flexibility at follow-up. Starting night work between baseline and follow-up (ß = 0.17, p < 0.01) and reporting night work at both baseline and follow-up (ß = 0.18, p < 0.01) were both positively associated with flexibility at follow-up, whereas stopping working nights was negatively (ß = -0.09, p < 0.05), associated with flexibility at follow-up. The personality traits languidity and flexibility show fairly high stability, albeit the mean scores were significantly reduced during the 7-8 years follow-up period. The results suggest that these personality traits are partly modifiable.

Sleep patterns among Norwegian nurses between the first and second wave of the COVID-19 pandemic.

BACKGROUND: Nurses are in the frontline and play an important role in the battle against the COrona VIrus Disease-2019 (COVID-19) pandemic. Sleep problems among health care workers are likely to increase due to the pandemic. However, it is conceivable that negative health outcomes related to the pandemic fluctuate with the infection rate waves of the pandemic. The present study aimed to investigate sleep patterns among Norwegian nurses, after the first wave, during a period with very low rates of COVID-19. METHODS: Data stemmed from the cohort study "SUrvey of Shift work, Sleep and Health (SUSSH)" among Norwegian nurses. A total of 1532 nurses responded one time to a questionnaire between June and September in 2020 including items about demographics and work, information about COVID-19 and quarantine, sleep patterns and changes in sleep patterns due to the pandemic. Descriptive statistics for all relevant variables were calculated and McNemar tests were used to compare categorical variables. RESULTS: The majority of nurses (84.2%) reported no change in sleep duration after the first wave of the COVID-19 pandemic compared to before, 11.9% reported less sleep, and 3.9% reported more sleep. Similarly, 82.4% of the nurses reported no change in their sleep quality, whereas 16.2% of the nurses reported poorer sleep quality after the first wave of the pandemic compared to before. The majority of nurses reported no change in their sleep schedule due to the pandemic, although 9.6% of the nurses reported to go to bed later and 9.0% woke up earlier than before the pandemic. CONCLUSIONS: Most existing literature exploring sleep among health care workers during the COVID-19 pandemic has been carried out during periods with high infection rates. In this study we aimed to investigate sleep patterns among Norwegian nurses following the first wave, during a period of low COVID-19 rates in Norway. Most of the nurses reported no change in neither sleep duration, sleep quality, bedtime, nor wake-up times compared to before the pandemic. Still, nearly 12% reported shorter sleep duration, and about 16% reported poorer sleep quality indicating that some nurses experienced worsening of their sleep following the pandemic.

Prevalence of Shift Work Disorder: A Systematic Review and Meta-Analysis.

Objectives: No systematic review or meta-analysis concerning the prevalence of shift work disorder (SWD) has been conducted so far. The aim was thus to review prevalence studies of SWD, to calculate an overall prevalence by a random effects meta-analysis approach and investigate correlates of SWD prevalence using a random-effects meta-regression. Methods: Systematic searches were conducted in ISI Web of Science, PsycNET, PubMed, and Google Scholar using the search terms "shift work disorder" and "shift work sleep disorder." No restrictions in terms of time frame were used. Included studies had to present original data on the prevalence of SWD in an occupational sample published in English. A total of 349 unique hits were made. In all, 29 studies were finally included from which two authors independently extracted data using predefined data fields. The meta-regression included four predictors (diagnostic criteria, study country, type of workers, and sample size). Results: The overall prevalence of SWD was 26.5% (95% confidence interval = 21.0-32.8). Cochran Q was 1,845.4 (df = 28, p < 0.001), and the I 2 was 98.5%, indicating very high heterogeneity across the observed prevalence estimates. Diagnostic criteria (International Classification of Sleep Disorders-2 = 0, International Classification of Sleep Disorders-3 = 1) and sample size were inversely related to SWD prevalence. Conclusions: The prevalence of SWD was high across the included studies. The between-study disparity was large and was partly explained by diagnostic criteria and sample size. In order to facilitate comparative research on SWD, there is a need for validation and standardization of assessment methodology as well as agreement in terms of sample restrictions.

Changes in work schedule affect the prevalence of shift work disorder among Norwegian nurses - a two year follow-up study.

This study aimed to explore how changes in the work schedule would affect the prevalence of Shift Work Disorder (SWD) over time. Two-year follow-up data from 1076 nurses participating in the longitudinal SUrvey of Shift work, Sleep and Health among Norwegian nurses (SUSSH) were included in the study. The questionnaires included measures of work-related factors, i.e., work schedule and numbers of night shifts and quick returns (QRs) worked the last year, as well as questions related to SWD according to the ICSD-3 diagnostic criteria at both baseline and at 2-year follow-up. Data were analyzed with paired samples t-tests, chi-square tests, and logistic regression analyses adjusting for sex and age. Terminating night work was the strongest predictor for recovering from SWD from baseline to follow-up (OR 10.91, 95% CI 6.11-19.46). Additionally, changing the work schedule from day work to night work from baseline to follow-up was the strongest predictor for developing SWD in the same period (OR 4.75, 95% CI 2.39-9.47). Reductions in number of nights (more than 10) and QRs (more than 10) worked the last year were associated with recovering from SWD between baseline and follow-up. Nurses who recovered from SWD had significantly reduced the mean number of night shifts worked the last year from 32.3 at baseline to 20.4 at follow-up (p = .001). Furthermore, an increase of more than 10 nights or more than 10 QRs worked the last year between baseline and follow-up predicted developing SWD. Nurses developing SWD between baseline and follow-up had significantly increased the mean number of nights worked the last year from 25.8 at baseline to 31.0 at follow-up (p =-.043). Changes in night work exposure were the strongest predictors for both recovering from or developing SWD from baseline to follow-up. Reducing exposure to night work and QRs were associated with recovering from SWD and increasing exposure to night work and QRs were associated with developing SWD. The results imply that unfavorable work schedules play a role in the development of sleep problems among nurses. These results may be useful when designing healthy working schedules.

Associations between exposure to workplace bullying and insomnia: a cross-lagged prospective study of causal directions.

OBJECTIVE: Workplace bullying has been established as a significant correlate of sleep problems. However, little is known regarding the causal direction between bullying and sleep. The aim of this study was to examine temporal relationships between bullying and symptoms of insomnia. METHODS: Reciprocal and prospective associations between exposure to workplace bullying and symptoms of insomnia were investigated in a national probability sample comprising 1149 Norwegian employees. Data stemmed from a two-wave full panel survey study with a 6-month time interval between the baseline and follow-up assessments. Models with stabilities, forward-, reverse-, and reciprocal associations were tested and compared using Structural Equation Modelling. Analyses were adjusted for age, gender, and the stability in the outcome variables over time. Workplace bullying was assessed with the nine-item Short Negative Acts Questionnaire. Insomnia was assessed with a previously validated three item scale reflecting problems with sleep onset, sleep maintenance, and early morning awakening. RESULTS: The forward association model, which showed that exposure to workplace bullying prospectively increased levels of insomnia (b = 0.08; p < 0.001), had best fit with the data [CFI = 0.94; TLI = 0.93; RMSEA = 0.049 (0.046-0.052)]. The reverse association model where insomnia influences risk of being subjected to bullying was not supported. CONCLUSION: Workplace bullying is a risk factor for later insomnia. There is a need for further studies on moderating and mediating variables that can explain how and when bullying influence sleep.