Relationship between insomnia and rest time between shifts among shift workers: A multicenter cross‐sectional study

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.

Synergistic interaction between long shifts and short rest periods on depression in shift workers: A cross-sectional study from Korea

BACKGROUND

Long shifts and short rest periods (SRP) between shifts are important factors that greatly affect shift workers' health. However, reports on the psychological effects of shift work, such as depression, have been inconsistent. Therefore, this study aimed to investigate the combined effect of long shifts and SRP on depression in shift workers.

METHODS

This cross-sectional study included 3295 shift workers in the sixth Korean Working Conditions Survey. The relative excess risk due to interaction (RERI) was computed to estimate the combined effect of long shifts and SRP on depression.

RESULTS

Depression in shift workers was not significantly associated with long shifts or SRP after adjustment, but the risk was significantly increased when exposed to both factors simultaneously (odds ratio 1.36, 95% confidence interval 1.03-1.79). The RERI between the two factors was statistically significant (p = 0.020), indicating a synergistic interaction with depression. Sensitivity analysis by occupation showed a significant interaction in the combined group of office and service workers (p = 0.034).

CONCLUSIONS

Simultaneous exposure to SRP and long shifts should be avoided when planning shift work schedules or devising health policies for shift workers. Special consideration is needed for healthcare and service workers, who may be particularly vulnerable to negative health impacts due to shift work.

Prevalence and risk factors associated with poor sleep among firefighters in Taiwan: An observational study

Sleep quality is directly correlated with overall health and quality of life. Firefighters have a higher workload and injury rate than those in other occupations. This study investigated the prevalence of and risk factors for poor sleep quality among firefighters in Taiwan. This cross-sectional study was conducted between November 2019 and August 2020. Sociodemographic information of the study participants was collected using a structured self-administered questionnaire. The Chinese version of the Pittsburgh Sleep Quality Index (PSQI) was used to evaluate the subjective sleep quantity and quality of firefighters during the previous month. A t test for continuous variables and χ2 test for categorical variables were performed for univariate analysis. Logistic regression analysis was conducted for multivariate analysis. Eight hundred eighty-nine firefighters completed the questionnaire during the study period, with a response rate of 88.9%. Among them, 447 (50.3%) reported poor sleep quality. Logistic regression analysis showed that female sex, longer work duration (>5 years) for firefighters, on-call shift work, and no leisure-time physical activity (LTPA) was significantly correlated with an increased risk of poor sleep quality. Advanced analysis of partaking in LTPA revealed that high-intensity LTPA is significantly associated with higher rates of poor sleep quality. In contrast, adequate rest after LTPA correlated with lower rates of poor sleep quality. Firefighters are at higher risk of poor sleep quality. Emphasis should be placed on firefighters' regular LTPA, particularly when experiencing sleep problems.

The significant association between quick return and depressive symptoms and sleep disturbances in paid workers: A nationwide survey

Objectives

Although many studies have examined the association between shift work and depression or insomnia, few studies have examined the relationship between quick return (QR) to work and depressive symptoms, regardless of shift work. Thus, in this study, we aimed to assess the association between depressive symptoms (DS)/sleep disturbances (SDs) and QR.

Methods

Data from the 6^th Korean Working Conditions Survey (2020) were used for this study. Paid workers aged between 20 and 65 years were included. DS were defined using the World Health Organization Well-Being Index (WHO-5) with a cut-off 50, and SD was defined as the occurrence of the following symptoms several times per month: difficulty in falling asleep, waking up in the middle of the night, or feeling tired even after waking up. QR was defined as "at least one case where the working interval between leaving work and the next day's work was < 11 h in the past month." Multivariable logistic regression was performed to estimate the adjusted odd ratios (aORs) and 95% confidence intervals (CIs). Mediation analysis was conducted to examine whether SD was a significant mediator in the association between QR and DS.

Results

Among the 27,554 participants, DS occurred in 8,277 patients, while SD occurred in 6,264 patients. The aORs (95% CIs) of DS and SD by QR were 2.01 (1.78-2.27) and 3.24 (2.87-3.66), respectively, after adjusting for age, gender, income, education, working hours, job status, working duration, region, shift work, and occupation. SD was a significant mediator in the association between QR and DS.

Conclusion

QR is significantly associated with DS or SD regardless of demographic factors and the working environment. The significant relationship between QR and DS may be mediated by SD.