Day-to-day variations in daily rest periods between working days and recovery from fatigue among information technology workers: One-month observational study using a fatigue app

Effects of work-related electronic communication during non-working hours after work from home and office on fatigue, psychomotor vigilance performance and actigraphic sleep: observational study on information technology workers

OBJECTIVES

This study examined the effects of work-related electronic communication (WREC) during non-working hours in the work from home or office setting on health.

METHODS

The study recruited 98 information technology workers in a 9-day observational study. They recorded work-life events (eg, work style (working mostly from home or the office) and duration of WREC during non-working hours) and subjective ratings (eg, current fatigue, sleepiness and depression) and wore a sleep actigraph to measure objective sleep variables before bedtime every day. They completed the Brief Psychomotor Vigilance Test (PVT-B) before bedtime for 4 days.

RESULTS

The frequency of WREC was significantly higher when working mostly from home than in the office (p<0.01). In addition, the duration of WREC was longer when working mostly from home than in the office (p<0.001). Linear or generalised linear mixed model analysis for fatigue, depression and PVT lapse revealed significant interaction effects between work style and WREC (all p<0.05). Post hoc analysis showed that the longer the WREC, the worse the fatigue and depression and the lower the lapse on working mostly from the office (all p<0.05).

CONCLUSIONS

Longer WREC is associated with worse fatigue and depression and lower lapse of PVT (higher alertness) before bedtime for working mostly from the office. Workers, especially those working from the office, should minimise WREC during non-working hours to maintain good health. Therefore, companies, managers and other relevant stakeholders should refrain from contacting workers during non-working hours.

Rest-activity rhythm associated with depressive symptom severity and attention among patients with major depressive disorder: a 12-month follow-up study

Introduction

Patients with depressive disorder demonstrate rest-activity rhythm disturbances and cognitive function impairment. This study examined the association of individual rest-activity rhythm changes over time with mood symptoms and attention.

Methods

We recruited 15 adult outpatients with a diagnosis of major depressive disorder from a single medical center and observed them for 12 months. Weekly rest-activity parameters, including rhythm characteristics generated from nonparametric circadian rhythm analysis, were retrieved from actigraphy data. Attention was evaluated weekly with a smartphone-based psychomotor vigilance test upon awakening. Depressive symptom severity was evaluated using the Beck Depression Inventory (BDI) fortnightly. The association of rest-activity parameters with BDI score and attention was examined using generalized linear mixed regression. A fixed-effects analysis was used to examine the association between rest-activity parameters and depressive episodes.

Results

An advanced bedtime and most active continuous 10 h starting time were associated with depressive symptom severity but also associated with higher vigilance test performance. A longer sleep duration, mainly due to an earlier bedtime, was associated with depressive symptom severity. Compared to remission, sleep duration was 27.8 min longer during depressive episodes, and bed time was 24 min earlier. A shorter sleep duration and increased activity during sleep were associated with poorer attention.

Discussion

Rest-activity rhythms change with mood symptoms among patients with depressive disorder. The circadian rhythms of rest-activity among patients with depressive disorder should be distinguished during various mood states in future studies.

The Joint Association of Daily Rest Periods and Sleep Duration with Worker Health and Productivity: A Cross-Sectional Web Survey of Japanese Daytime Workers

A daily rest period (DRP) is a daily inter-work interval that contains sleep opportunity. This study investigates the joint association of DRP and sleep duration with worker health and productivity. A total of 13,306 Japanese daytime workers participated in this web-based cross-sectional survey. Participants reported on their DRPs and sleep duration; moreover, sleep difficulties, mental health, and presenteeism were assessed by the standardized questionnaires. The participants were divided into 10 groups based on their DRPs and sleep duration. Logistic regression analyses showed that the combination of quick return (QR: DRP of <11 h) and short sleep duration (<6 h) was found to be significantly associated with sleep difficulties (odds ratio [OR] = 4.45, 95% confidence interval [CI] = 2.83-7.01), poor mental health (OR = 3.04, 95% CI = 1.79-5.15), and presenteeism (OR = 2.35, 95% CI = 1.47-3.77) compared with the reference group (the combination of adequate DRP [15 h] and a normal sleep duration [≥6 h]). The combination of QR and normal sleep duration or adequate DRP and short sleep duration was significantly associated with high ORs for the outcomes. QR, short sleep duration, or both negatively affect worker health and productivity.

Impact of sleep timing on attention, sleepiness, and sleep quality among real-life night shift workers with shift work disorder: a cross-over clinical trial

STUDY OBJECTIVES

To examine the effect of sleep timing intervention on sleep quality, attention, and sleepiness at work among night shift workers with shift work disorder.

METHODS

We recruited 60 real-life night shift workers through advertisements to participate this cross-over clinical trial. Shift work disorder was confirmed with interview and sleep log. Participants were designated to follow evening sleep (15:00-23:00) and morning sleep (09:00-17:00) schedules in a randomized order. Chronotype was confirmed by the Munich Chronotype Questionnaire. Sleep behaviors and light exposure were recorded using actigraphy. Outcome measures were sleepiness evaluated by the Karolinska Sleepiness Scale, sleep quality evaluated by the Pittsburgh Sleep Quality Index, and attention performance assessed with psychomotor vigilance test. Differences in outcome between the morning and evening sleep schedules were compared using repeated measures ANOVA.

RESULTS

The participants slept for longer durations during evening sleep schedules compared with morning sleep schedules. Lower sleepiness scores, higher sleep quality, and shorter reaction times and less lapse numbers in the psychomotor vigilance test were observed for participants during evening sleep schedules than morning sleep schedules after adjustment for light exposure and sleep duration. Significant interaction effects were observed for reaction time and lapse number between chronotype and sleep schedule, where the differences between sleep schedules were most prominent among those with late chronotypes.

CONCLUSIONS

It is recommended that night shift workers with shift work disorder arrange to sleep in the evening instead of the morning for better sleep and attention performance, especially those with late chronotypes.

TRIAL REGISTRATION

Sleep Schedule Intervention Study Among Night Shift Workers, https://clinicaltrials.gov/ct2/show/NCT04160572, ClinicalTrials.gov Identifier: NTC04160572.

Work e-mail after hours and off-job duration and their association with psychological detachment, actigraphic sleep, and saliva cortisol: A 1-month observational study for information technology employees

Objective

A sufficient duration of time off after work is necessary to ensure workers’ health. Better quality of off‐job time can also facilitate recovery from fatigue, but its quantitative influence is largely unknown. We aimed to examine how off‐job time quality (as measured by the frequency of emailing after work), and off‐job duration is associated with psychological detachment, actigraphic sleep, and saliva cortisol using a 1‐month observational study.

Methods

The participants were 58 daytime employees working at an information technology company. Sleep actigraphy and saliva cortisol as well as self‐reported outcomes were repeatedly measured for 1 month. Two‐way (work e‐mail frequency × off‐job time) multilevel mixed‐effects linear regression analyses were performed in both continuous and categorical variables.

Results

The frequency of work e‐mailing after hours was significantly associated with self‐reported outcomes and actigraphic sleep quality, while a significant association was not found in cortisol awakening responses and actigraphic sleep duration. A significantly larger cortisol response after awakening was found in shorter, rather than longer, durations of off‐job time. Self‐reported detachment, rumination and carry‐over fatigue showed significant interactions between work e‐mail and off‐job time, suggesting that worse outcomes were found in a higher frequency of work e‐mail even when employees had longer amounts of off‐job time.

Conclusion

Our findings suggest that ensuring the quality and duration of off‐job time is beneficial for recovery from work with sufficient sleep. Specifically, the frequency of e‐mailing after work should be minimized to make recovery complete.

Prospective changes in sleep problems in response to the daily rest period among Japanese daytime workers: A longitudinal web survey

The daily rest period (DRP) is the daily inter‐work interval and can include a sleep opportunity, leisure time, and other non‐work time. A longer DRP may allow workers to increase time in bed (TIB) and adjust sleep timing, and that may reduce sleep problems such as short sleep duration, sleep debt, social jetlag, and poor sleep quality. The present study examined the longitudinal association between the DRP and these sleep problems among Japanese daytime workers. The DRP, TIB on workdays, sleep quality (Pittsburgh Sleep Quality Index [PSQI]), sleep debt and social jetlag were measured in November 2016 (n = 10,000) and February 2019 (n = 3,098). Of these, 955 permanent daytime workers were divided into five groups based on the change in the DRP duration: shortened ≥2 hr, shortened ≥1 hr, no change (<1 hr), extended ≥1 hr and extended ≥2 hr. Linear mixed‐model analysis revealed significant interaction (group × time) effects on the TIB, PSQI score and sleep debt (all p < 0.001), but not on social jetlag (p = 0.476). Post hoc comparisons revealed that the TIB was decreased, and the sleep debt was increased in the shortened ≥2 hr group, whereas the TIB was increased and PSQI score was improved in the extended ≥2 hr group (all p < 0.01). These findings suggest that an extension of the DRP improves sleep quantity and quality but not sleep debt and social jetlag. Aside from extending the DRP, ensuring a sufficient sleep duration and adjusting sleep timing during the DRP may also be needed to prevent sleep problems.

Association of rotating shift work schedules and the use of prescribed sleep medication: A prospective cohort study

We examined whether working rotating shifts, with or without night work, is associated with the purchase of prescribed sleep medication, and whether the association is dependent on age. Data were obtained from a longitudinal cohort study of Finnish public sector employees who responded to questions on work schedule and background characteristics in 2000, 2004 and 2008. The data were linked to national register data on redeemed prescriptions of hypnotic and sedative medications, with up to 11 years of follow-up. Age stratified Cox proportional hazard regression models were computed to examine incident use of medication comparing two groups of rotating shift workers (those working shifts that included night shifts and those whose schedules did not include night shifts) with day workers who worked in a similar range of occupations. Shift work with night shifts was associated with increased use of sleep medication in all age groups, after adjustments for sex, occupational status, marital status, alcohol consumption, smoking and physical activity levels (hazard ratio [HR], [95% confidence interval, CI] 1.14 [1.01-1.28] for age group ≤39 years; 1.33 [1.19-1.48] for age group 40-49 years; 1.28 [1.13-1.44] for age group ≥50 years). Shift work without nights was associated with medication use in the two older age groups (HR [95% CI] 1.14 [1.01-1.29] and 1.17 [1.05-1.31] for age groups 40-49 years and >50 years, respectively). These findings suggest that circadian disruption and older age puts rotating shift workers, and especially those who work nights, at increased risk of developing clinically significant levels of sleep problems.

Shorter sleep duration is associated with potential risks for overwork-related death among Japanese truck drivers: use of the Karoshi prodromes from worker's compensation cases

Purpose

We aimed to cross-sectionally investigate how work and sleep conditions could be associated with excessive fatigue symptoms as an early sign of Karoshi (overwork-related cerebrovascular and cardiovascular diseases; CCVDs).

Methods

We distributed a questionnaire regarding work, sleep, and excessive fatigue symptoms to 5410 truck drivers, as the riskiest occupation for overwork-related CCVDs, and collected 1992 total samples (response rate: 36.8%). The research team collected 1564 investigation reports required for compensation for Karoshi. Of them, 190 reports listed the prodromes of Karoshi, which were used to develop the new excessive fatigue symptoms inventory.

Results

One-way analyses of variance showed that the excessive fatigue symptoms differed significantly by monthly overtime hours (p < 0.001), daily working time (p < 0.001), work schedule (p = 0.025), waiting time on-site (p = 0.049), number of night shifts (p = 0.011), and sleep duration on workdays (p < 0.001). Multivariate mixed-model regression analyses revealed shorter sleep duration as the most effective parameter for predicting excessive fatigue symptoms. Multiple logistic regression analysis confirmed that the occurrences of CCVDs were significantly higher in the middle [adjusted ORs = 3.56 (1.28–9.94)] and high-score groups [3.55 (1.24–10.21)] than in the low-score group.

Conclusion

The findings suggested that shorter sleep duration was associated more closely with a marked increase in fatigue, as compared with the other work and sleep factors. Hence, ensuring sleep opportunities could be targeted for reducing the potential risks of Karoshi among truck drivers.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00420-021-01655-5.

Daytime Workers with Longer Daily Rest Periods Have Smaller Sleep Debt and Social Jetlag: A Cross-Sectional Web Survey

Objectives: The work interval duration between the end of one workday and the start of the following workday is referred to as the daily rest period (DRP). The present study examined whether DRP - a proxy for sleep opportunity between work shifts - is associated with indicators of sleep debt and social jetlag among daytime workers. Methods: We used a web-based survey to gather data on demographics, average DRP in the previous month, time in bed (TIB), bedtime, wake-up time, and sleep timing on workdays and non-workdays. The Japanese daytime workers (n = 3,914) were divided into seven DRP groups (hours) as follows: <11, 11, 12, 13, 14, 15, and ≥16. Results: The two-way analyses of covariance (DRP group x day) for TIB, mid-sleep as sleep timing, bedtime, and wake-up time showed significant interactions (all p < .001). Specifically, TIB was significantly shorter, and mid-sleep and wake-up time were significantly earlier on workdays than on non-workdays, across all DRP groups (all p < .001). Additionally, the different values for TIB (sleep debt), sleep timing (social jetlag), bedtime, and wake-up time were calculated by subtracting workdays from non-workdays. The trend analysis showed that workers with longer DRP (sleep opportunity) had smaller differences in TIB, sleep timing, and wake-up time between workdays and non-workdays (all p < .001). Conclusions: Overall, daytime workers reported significant sleep debt and misalignment between work and free sleep-wake periods. However, workers with shorter DRPs (less sleep opportunity between shifts) reported significantly greater amounts of sleep debt and social jetlag than did workers with longer DRPs.