Sleep, mental health and physical health in new shift workers transitioning to shift work: Systematic review and meta-analysis.

This systematic review and meta-analysis (PROSPERO registration CRD42022309827) aimed to describe how shift work impacts new workers' sleep, mental health, and physical health during the transition to shift work and to consolidate information regarding predictors of shift work tolerance (SWT) during this transition period. Inclusion criteria included: new shift workers; sleep, mental health, or physical health outcomes; prospective study design with the first timepoint assessing workers within three months of starting shift work; and written in English. Searches from six databases returned 12,172 articles as of August 2023. The final sample included 48 papers. Publication quality and risk of bias was assessed using the critical appraisal skills program. Forty-five studies investigated longitudinal changes in sleep, mental health, or physical health outcomes and 29 studies investigated predictors of SWT (i.e., better sleep, mental and physical health). Sleep and mental health outcomes worsened following the onset of shift work, while physical health did not significantly change. Pre-shift work mental health, sleep, and work characteristics predicted SWT later in workers' careers. Shift work adversely impacts new workers' sleep and mental health early in their career, and interventions before beginning shift work are needed to promote better SWT.

Association between burnout and adherence with mask usage and additional COVID-19 prevention behaviours: findings from a large-scale, demographically representative survey of US adults.

OBJECTIVES: Studies have found associations between occupational burnout symptoms and reduced engagement with healthy behaviours. We sought to characterise demographic, employment and sleep characteristics associated with occupational burnout symptoms, and to evaluate their relationships with adherence to COVID-19 prevention behaviours (mask usage, hand hygiene, avoiding gatherings, physical distancing, obtaining COVID-19 tests if potentially infected). METHODS: During December 2020, surveys were administered cross-sectionally to 5208 US adults (response rate=65.8%). Quota sampling and survey weighting were employed to improve sample representativeness of sex, age and race and ethnicity. Among 3026 employed respondents, logistic regression models examined associations between burnout symptoms and demographic, employment and sleep characteristics. Similar models were conducted to estimate associations between burnout and non-adherence with COVID-19 prevention behaviours. RESULTS: Women, younger adults, unpaid caregivers, those working more on-site versus remotely and those with insufficient or impaired sleep had higher odds of occupational burnout symptoms. Burnout symptoms were associated with less frequent mask usage (adjusted odds ratio (aOR)=1.7, 95% CI 1.3-2.1), hand hygiene (aOR=2.1, 95% CI 1.7-2.7), physical distancing (aOR=1.3, 95% CI 1.1-1.6), avoiding gatherings (aOR=1.4, 95% CI 1.1-1.7) and obtaining COVID-19 tests (aOR=1.4, 95% CI 1.1-1.8). CONCLUSIONS: Disparities in occupational burnout symptoms exist by gender, age, caregiving, employment and sleep health. Employees experiencing occupational burnout symptoms might exhibit reduced adherence with COVID-19 prevention behaviours. Employers can support employee health by addressing the psychological syndrome of occupational burnout.

Sleep and mental health in recruit paramedics: a 6-month longitudinal study.

STUDY OBJECTIVES: To explore potential relationships and longitudinal changes in sleep and mental health in recruit paramedics over the first 6 months of work, and whether sleep disturbances pre-emergency work predict future mental health outcomes. METHODS: Participants (N = 101, 52% female, Mage = 26 years) completed questionnaires prior to (baseline), and after 6 months of emergency work to assess for symptoms of insomnia, obstructive sleep apnea, post-traumatic stress disorder (PTSD), depression, anxiety, and trauma exposure. At each timepoint, participants also completed a sleep diary and wore an actigraph for 14 days to assess sleep patterns. Correlations between baseline sleep and mental health were conducted and changes in these variables across timepoints were examined using linear mixed models. Hierarchical regressions assessed whether sleep at baseline predicted mental health at follow-up. RESULTS: Insomnia and depression symptoms, and total sleep time increased while sleep onset latency decreased across the first 6 months of emergency work. Participants experienced an average of 1 potentially traumatic event during the 6-month period. Baseline insomnia predicted increased depression symptoms at the 6-month follow-up, while baseline wake after sleep onset predicted follow-up PTSD symptoms. CONCLUSION: Results highlight an increase in insomnia and depression across the initial months of emergency work, while sleep disturbances before emergency work were identified as potential risk factors for the development of depression and PTSD among paramedics in their early career. Screening and early interventions targeting poor sleep at the beginning of emergency employment may assist in reducing the risk of future mental health outcomes in this high-risk occupation.

Mental health risk factors for shift work disorder in paramedics: A longitudinal study.

OBJECTIVES: Depression and anxiety are prominent in paramedics, as is the prevalence of shift work disorder (SWD), a circadian sleep condition comorbid with mental health disorders. However, the role of mental health risk factors for SWD is largely unknown. This study investigated whether mental health levels in recruit paramedics before shift work predicted greater risk of SWD at 6-months into their career and explored whether shift and sleep factors mediated this relationship. DESIGN: A longitudinal study. SETTING: Victoria, Australia. PARTICIPANTS: Recruit paramedics were assessed at baseline (n = 101; ie, pre-shift work) and after 6-months (n = 93) of shift and emergency work. MEASUREMENTS: At both time points, participants completed self-reported measures of depression (Patient Health Questionnaire-9), anxiety (Generalized Anxiety Disorder Questionnaire-7), and SWD (SWD-Screening Questionnaire). Participants also filled a sleep and work diary for 14-days at each timepoint. RESULTS: After 6-months of emergency work 21.5% of paramedics had a high SWD risk. Logistic regression models showed baseline depression predicted 1.24-times greater odds for SWD at 6-months. Through Lavaan path analysis we found shift and sleep variables did not mediate the relationship between baseline mental health and SWD risk. Baseline depression was associated with increased sleepiness levels following paramedics' major sleep periods at 6-months. Pre-existing depression levels also predicted greater perceived nightshift workload. CONCLUSIONS: Our results highlight depression symptoms before emergency work are a risk factor for SWD within 6-months of work. Depression represents a modifiable risk factor amenable to early interventions to reduce paramedics' risk of SWD.

The impact of break duration, time of break onset, and prior shift duration on the amount of sleep between shifts in heavy vehicle drivers.

This study aimed to examine the impact of break duration between consecutive shifts, time of break onset, and prior shift duration on total sleep time (TST) between shifts in heavy vehicle drivers (HVDs), and to assess the interaction between break duration and time of break onset. The sleep (actigraphy and sleep diaries) and work shifts (work diaries) of 27 HVDs were monitored during their usual work schedule for up to 9 weeks. Differences in TST between consecutive shifts and days off were assessed. Linear mixed models (followed by pairwise comparisons) assessed whether break duration, prior shift duration, time of break onset, and the interaction between break duration and break onset were related to TST between shifts. Investigators found TST between consecutive shifts (mean [SD] 6.38 [1.38] h) was significantly less than on days off (mean [SD] 7.63 [1.93] h; p < 0.001). Breaks starting between 12:01 and 8:00 a.m. led to shorter sleep (p < 0.05) compared to breaks starting between 4:01 and 8:00 p.m. Break durations up to 7, 9, and 11 h (Australian and European minimum break durations) resulted in a mean (SD) of 4.76 (1.06), 5.66 (0.77), and 6.41 (1.06) h of sleep, respectively. The impact of shift duration prior to the break and the interaction between break duration and time of break were not significant. HVDs' sleep between workdays is influenced independently by break duration and time of break onset. This naturalistic study provides evidence that current break regulations prevent sufficient sleep duration in this industry. Work regulations should evaluate appropriate break durations and break onset times to allow longer sleep opportunities for HVDs.

Cardiometabolic, Dietary and Physical Health in Graduate Paramedics during the First 12-Months of Practice - A Longitudinal Study.

Objective: Shift work is an established risk factor for poor health yet is necessary for paramedics to provide continuous care to the public. It is unknown how early into a career shift work may begin to impact health. This study sought to identify changes in cardiometabolic health, diet, aerobic capacity, physical activity and health-related quality of life (HRQoL) in graduate paramedics during the first 12-months of their career.Methods: Fifty-six paramedics with no history of regular shift work (28 female, 28 male; median age 24.5, IQR 23-26 years) were recruited for this study. Dietary patterns (food frequency questionnaires) and HRQoL (36-Item Short Form Questionnaire) were assessed at baseline, 6- and 12-months. Body weight, body mass index (BMI) and blood samples (fasting lipids, glucose, insulin and C-reactive protein) were measured at baseline and 12-months to ascertain cardiometabolic health risk. A subset of participants (n = 19; 10 female, 9 male) wore a physical activity monitor for 12 months and completed baseline and 12-month maximal aerobic capacity assessments (V̇O2max).Results: Body weight and BMI decreased in males and increased in females (-0.7% versus 1.7%, p = 0.02). HRQoL and dietary intake did not change over 12-months, except for a small decrease in fat intake (-1%). Consumption of core/healthy foods was lower than recommended at all timepoints. Biomarkers of cardiometabolic health were within normal range and did not change over 12-months, excepting insulin where a small non-significant increase was seen (+0.5 mIU/L, p = 0.61). Baseline V̇O2max was 41.4 (37.1-49.1) ml.kg-1.min-1, with no change noted at 12-months. Comparison of quarterly physical activity data showed no difference in steps per day (p = 0.47) or moderate to vigorous physical activity (MVPA, p = 0.92) across the 12-months. Paramedics completed less MVPA on day shifts compared to rostered days off (-14.68 minutes, p = 0.04).Conclusions: Dietary patterns, HRQoL, cardiometabolic health, aerobic capacity and physical activity levels did not change meaningfully in the first year of practice. Some dietary behaviors and physical activity levels could be improved and may mitigate health effects of exposure to shift work. Long-term follow-up of this group may aid in developing programs to enhance health for paramedics and other health workers.

The impact of 7-hour and 11-hour rest breaks between shifts on heavy vehicle truck drivers' sleep, alertness and naturalistic driving performance.

BACKGROUND: An inadequate rest break between shifts may contribute to driver sleepiness. This study assessed whether extending the major rest break between shifts from 7-hours (Australian industry standard) to 11-hours, improved drivers' sleep, alertness and naturalistic driving performance. METHODS: 17 heavy vehicle drivers (16 male) were recruited to complete two conditions. Each condition comprised two 13-hour shifts, separated by either a 7- or 11-hour rest break. The initial 13-hour shift was the drivers' regular work. The rest break and following 13-hour shift were simulated. The simulated shift included 5-hours of naturalistic driving with measures of subjective sleepiness, physiological alertness (ocular and electroencephalogram) and performance (steering and lane departures). RESULTS: 13 drivers provided useable data. Total sleep during the rest break was greater in the 11-hour than the 7-hour condition (median hours [25th to 75th percentile] 6.59 [6.23, 7.23] vs. 5.07 [4.46, 5.38], p = 0.008). During the simulated shift subjective sleepiness was marginally better for the 11-hour condition (mean Karolinska Sleepiness Scale [95th CI] = 4.52 [3.98, 5.07] vs. 5.12 [4.56, 5.68], p = 0.009). During the drive, ocular and vehicle metrics were improved for the 11-hour condition (p<0.05). Contrary to expectations, mean lane departures p/hour were increased during the 11-hour condition (1.34 [-0.38,3.07] vs. 0.63 [-0.2,1.47], p = 0.027). CONCLUSIONS: Extending the major rest between shifts substantially increases sleep duration and has a modest positive impact on driver alertness and performance. Future work should replicate the study in a larger sample size to improve generalisability and assess the impact of consecutive 7-hour major rest breaks.

The impact of shift work schedules on PVT performance in naturalistic settings: a systematic review.

OBJECTIVE: The Psychomotor Vigilance Test (PVT) is considered the gold standard for detecting sleep loss and circadian misalignment related changes in performance in laboratory and field settings. This short 3-, 5- or 10-min test appraises an individual's sustained vigilant attention on a visual stimulus through reaction time, false starts and performance lapses. The PVT has been widely used as a measure to assess vigilant attention among shift workers, but information evaluating the application and performance of this test in different naturalistic shift work settings is limited. The purpose of this review is to synthesise and evaluate existing literature which has used the PVT to assess and monitor psychomotor performance in response to shift work schedules and rosters performed in real-world settings. METHODS: A systematic search of studies examining PVT performance in response to 24/7 shift work schedules (e.g., day, afternoon, evening and night shifts) performed under naturalistic conditions was conducted. Articles were identified by searching Medline, Embase, CINHAL and PsycINFO databases in April 2020. RESULTS: The search yielded 135 results, of which 16 publications were suitable to be included in this review. Articles were grouped according to when the PVT was applied to a research cohort, which included (a) multiple instances per shift, (b) commencement and cessation of shift and (c) other varying times. CONCLUSIONS: This review suggests PVT performance is typically congruent across studies when the test is applied at generally consistent time intervals. The lack of research concerning the use of the PVT during extended duty shifts (e.g., shifts and on call work > 30 h) is an area for future research.

The impact of heart rate-based drowsiness monitoring on adverse driving events in heavy vehicle drivers under naturalistic conditions.

OBJECTIVES: This study examined the influence of a wrist-worn heart rate drowsiness detection device on heavy vehicle driver safety and sleep and its ability to predict driving events under naturalistic conditions. DESIGN: Prospective, non-randomized trial. SETTING: Naturalistic driving in Malaysia. PARTICIPANTS: Heavy vehicle drivers in Malaysia were assigned to the Device (n = 25) or Control condition (n = 34). INTERVENTION: Both conditions were monitored for driving events at work over 4-weeks in Phase 1, and 12-weeks in Phase 2. In Phase 1, the Device condition wore the device operated in the silent mode (i.e., no drowsiness alerts) to examine the accuracy of the device in predicting driving events. In Phase 2, the Device condition wore the device in the active mode to examine if drowsiness alerts from the device influenced the rate of driving events (compared to Phase 1). MEASUREMENTS: All participants were monitored for harsh braking and harsh acceleration driving events and self-reported sleep duration and sleepiness daily. RESULTS: There was a significant decrease in the rate of harsh braking events (Rate ratio = 0.48, p < 0.05) and a fall in subjective sleepiness (p < 0.05) when the device was operated in the active mode (compared to the silent mode). The device predicted when no driving events were occurring (specificity=98.81%), but had low accuracy in detecting when a driving event did occur (sensitivity=6.25%). CONCLUSIONS: Including drowsiness detection devices in fatigue management programs appears to alter driver behaviour, improving safety despite the modest accuracy. Longer term studies are required to determine if this change is sustained.

Firefighter's Acute Inflammatory Response to Wildfire Suppression.

OBJECTIVES: The purpose of this study was to determine the inflammatory response to a 12-hour wildfire suppression shift, in firefighters attending the "Black Saturday" natural disaster. METHODS: Thirty-eight male volunteer firefighters provided venous blood samples before and after a 12-hour firefighting shift. Pre- to post-shift changes in pro-inflammatory (Interleukin [IL]-1ß, IL-2, IL-6, IL-8, IL-12P70, granulocyte macrophage-colony stimulating factor [GM-CSF], tumor necrosis factor-alpha [TNF-α], interferon-gamma [IFNγ]), and anti-inflammatory (IL-4, IL-5, IL-7, IL-10, IL-13) cytokines were measured with paired sample t tests, or Wilcoxon t tests for non-parametric data. RESULTS: Interleukin (IL)-6 (P = 0.003) and IL-8 (P = 0.017) were significantly increased following 12-hours of wildfire suppression. There was also a significant decrease in IL-10 (P = 0.021). CONCLUSIONS: The observed acute inflammatory response may have resulted from multiple stressors including physical exertion, thermal strain, or smoke inhalation experienced during the shift, and may be a necessary response for the body to adapt to stressor exposure.

Associations between shift work characteristics, shift work schedules, sleep and burnout in North American police officers: a cross-sectional study.

OBJECTIVES: To examine associations between shift work characteristics and schedules on burnout in police and whether sleep duration and sleepiness were associated with burnout. METHODS: Police officers (n=3140) completed the Maslach Burnout Inventory (emotional exhaustion, depersonalisation, personal accomplishment) and self-reported shift schedules (irregular, rotating, fixed), shift characteristics (night, duration, frequency, work hours), sleep duration and sleepiness. RESULTS: Irregular schedules, long shifts (≥11 hours), mandatory overtime, short sleep and sleepiness were associated with increased risk of overall burnout in police. Police working a greater frequency of long shifts were more likely to have emotional exhaustion (adjusted OR 1.91, 95% CI 1.35 to 2.72) than those not working long shifts. Night shifts were associated with depersonalisation (1.32, 1.05 to 1.66) compared with not working nights. Police working mandatory overtime had increased risk of emotional exhaustion (1.37, 1.14 to 1.65) than those who did not. Compared with fixed schedules, irregular schedules were associated with emotional exhaustion and depersonalisation (1.91, 1.44 to 2.54 and 1.39, 1.02 to 1.89, respectively). Police sleeping <6 hours were more likely to have emotional exhaustion (1.60, 1.33 to 1.93) than those sleeping longer, and excessive sleepiness was associated with emotional exhaustion (1.81, 1.50 to 2.18). CONCLUSIONS: Irregular schedules and increased night shifts, sleep disturbances and work hours were related to higher burnout risk in police. Future research should evaluate work schedules in law enforcement that optimise shift duration and frequency, and increase consistency in scheduling and control over work hours to limit burnout in police.

Recommendations for current and future countermeasures against sleep disorders and sleep loss to improve road safety in Australia.

The Australian National Road Safety Strategy 2011-2020 framed a 19-point action plan targeting a 30% reduction in road deaths by 2020. In achieving a 9% reduction to date, it is likely to fail this target. Sleep disorders and sleep loss did not feature prominently in this strategy, despite their high prevalence and effect on drowsiness and crashes. This article gathers sleep experts to provide recommendations addressing driver education and legislation to assist the response to this public health problem. Developments in drowsiness detection and sleep disorders management are also presented that offer innovative countermeasures that could enhance road safety beyond 2020.

Associations between sleep disturbances, mental health outcomes and burnout in firefighters, and the mediating role of sleep during overnight work: A cross-sectional study.

This study investigated whether sleep disorder risk and mental health outcomes in firefighters were associated with burnout, particularly emotional exhaustion, and examined the mediating role of sleep at work in these relationships. A secondary aim was to investigate associations between habitual sleep characteristics and burnout. North American firefighters (n = 6,307) completed the Maslach Burnout Inventory (emotional exhaustion, depersonalisation, personal accomplishment), and were screened for sleep disorders and self-reported current mental health conditions and sleep characteristics. Multiple logistic regression analyses examined associations between sleep, mental health outcomes and burnout. Firefighters screening positive for a sleep disorder, particularly insomnia, had increased risk of emotional exhaustion (adjusted odds ratio 3.78, 95% confidence interval 2.97-4.79). Firefighters self-reporting a current mental health condition were at greater risk of emotional exhaustion (adjusted odds ratio 3.45, 95% confidence interval 2.79-4.27). Sleep during overnight work mediated the impact of having a sleep disorder and mental health condition on high burnout. Sleepiness and sleep deficit (difference between required and actual sleep), even in firefighters without sleep disorder risk, were associated with depersonalisation (adjusted odds ratio 1.65, 95% confidence interval 1.34-2.03 and adjusted odds ratio 1.29, 95% confidence interval 1.06-1.57, respectively) and low personal accomplishment (adjusted odds ratio 1.25, 95% confidence interval 1.07-1.47 and adjusted odds ratio 1.17, 95% confidence interval 1.01-1.35, respectively). Sleep and mental health problems were associated with increased risk of burnout in firefighters, and sleep during overnight work mediated these relationships. The results suggest the need to examine the effectiveness of occupational interventions that improve the opportunity for sleep, together with screening for and treating sleep disorders, to reduce burnout risk.

Personal sleep debt and daytime sleepiness mediate the relationship between sleep and mental health outcomes in young adults.

BACKGROUND: Sleep duration and chronotype (i.e., morningness-eveningness) are associated with increased depression and anxiety risk, but differences in individual sleep need and lifestyle may mean these sleep parameters do not present the same risk across all individuals. This study explored the mediating role of sleep debt and daytime sleepiness in the relationship between sleep and mental health symptoms in young adults, a particularly vulnerable population. METHODS: Young adult university students (n = 2,218) and young adults from the general population in the United States (n = 992) provided estimates of actual and optimal sleep duration, and completed validated measures of sleepiness, chronotype, and depression and anxiety risk. Mediation models examining sleepiness and sleep debt (i.e., difference between optimal and actual sleep) as parallel mediators were tested. RESULTS: Sleepiness and sleep debt mediated the relationship between short sleep and depression and anxiety risk in the university sample, while sleepiness mediated these relationships in the general population sample. Sleepiness and sleep debt also mediated the impact of evening-type preferences on depression and anxiety risk in university students, but no mediation of this effect was found in young adults from the general population. CONCLUSIONS: This study reports potential mediating mechanisms related to the increased mental health risk conferred by short sleep and evening chronotype. These results have implications for how primary care physicians assess psychopathology risk, arguing for a focus on the assessment of daytime sleepiness and sleep debt in university populations, while for young adults in the general population, these factors may be less important.