The Japanese version of the reduced morningness-eveningness questionnaire.

Circadian typology, or "morningness" and "eveningness," is generally assessed using the Morningness-Eveningness Questionnaire (MEQ), a 19-item scale that could be burdensome in large-scale surveys. To overcome this, a 5-item version known as the reduced morningness-eveningness questionnaire (rMEQ), which is sensitive to the assessment of circadian typology, was developed; however, a validated Japanese version of the rMEQ is yet to be established. This study aimed to develop and validate the Japanese version of the rMEQ. Five essential items for the rMEQ were selected from existing Japanese MEQ data (N = 2,213), and the rMEQ was compiled. We conducted a confirmatory factor analysis for the psychometric properties of the rMEQ and confirmed its robust one-factor structure for evaluating morningness-eveningness (GFI = 0.984, AGFI = 0.951, CFI = 0.935, and RMSEA = 0.091). Reliability was evaluated via internal consistency of rMEQ items using Cronbach's α and McDonald's ω, and the values were 0.618 and 0.654, respectively. The rMEQ scores strongly correlated with MEQ (ρ = 0.883, p < 0.001), and classification agreement (Morning, Neither, and Evening types) between rMEQ and MEQ was 77.6% (Cramer's V = 0.643, Weighted Cohen's κ = 0.72), confirming the validity. The Japanese rMEQ may be a valuable tool for the efficient assessment of circadian typologies.

The association between work interval regularity and sleep regularity: a 2-week observational study in daytime employees.

OBJECTIVES: Several health issues are associated with irregular sleep patterns. However, it is unclear what causes workers to sleep irregularly. The work interval (WI) between the end of one day's working hours and the start of the next day's working hours contains sleep opportunities, and an irregular WI may result in irregular sleep. This study investigated this association among Japanese daytime workers. METHODS: This study recruited 141 daytime workers without shiftwork for a 14-day observational study. Participants reported the WI duration, WI timing, time in bed (TIB: difference between bedtime and wake-up time), and bedtime timing every day before bedtime. The SD over 14 days was used to calculate the regularity scores. Logistic regression analysis was performed. The dependent variables were ≥60 minutes of TIB SD and bedtime timing SD, whereas the independent variables were WI duration and timing SD. RESULTS: The odds ratios (ORs) (95% CIs) for ≥60 minutes of TIB SD across categories of WI duration SD were 1.000 (reference) for <30 minutes, 1.344 (0.337-5.360) for 30-60 minutes, and 4.743 (1.441-15.607) for ≥60 minutes. The ORs (95% CIs) for ≥60 min of bedtime timing SD across categories of WI timing SD were 1.000 for <30 minutes, 4.154 (1.574-10.965) for 30-60 minutes, and 7.714 (2.124-28.015) for ≥60 minutes. CONCLUSIONS: Regularity of WI was associated with regularity of sleep. To ensure worker health, workers should have regular WI, and if they are exposed to irregular WI, they should make every effort to maintain regular sleep.

Cross-sectional associations of weekly time, social context, and motivation of exercise with mental health among workers.

PURPOSE: Exercise is considered a strategy to promote mental health among workers. However, the optimal exercise conditions that promote mental health benefits for workers are still unclear. This study examined the cross-sectional associations of weekly exercise time duration, social context of exercise, and exercise motivation levels with the mental health among Japanese workers. METHODS: A web-based cross-sectional questionnaire survey was conducted among 18,902 workers, aged 20-59 years. The mental health variables (psychological distress, psychological stress reaction, physical stress reaction, job satisfaction, and work engagement), exercise participation (non-exercisers, exercisers), and demographic factors of all responders were measured. Weekly exercise time, social context of exercise (alone only, with others only, both alone and with others), and exercise motivation (non-regulation, external/introjected regulation, identified regulation, integrated regulation, and internal regulation) were also measured amongst exercisers. After adjusting for demographic factors, multiple regression analyses were conducted. RESULTS: Exercisers had significantly lower psychological distress, lower psychological and physical stress reactions, higher job satisfaction, and higher work engagement than non-exercisers. Among exercisers, while weekly exercise time duration and social context of exercise were not clearly and robustly associated with mental health variables, respondents with intrinsic regulation had significantly lower psychological distress, lower psychological and physical stress reaction, higher job satisfaction, and higher work engagement than those with lower self-determined motivations. CONCLUSIONS: This study found that more self-determined exercise motivation is closely associated with advantageous mental health variables, than the duration or the social context of exercise among Japanese workers.

Protocol for a web-based study on the work environment and daily lifestyle of Japanese employees.

Mental health problems are prevalent among the working population and must be resolved. We conducted a web-based large-scale study of workers, including a baseline survey and two follow-up surveys, to investigate the associations between self-care behaviors in daily life (e.g., stress coping, sleep, diet, and exercise), work environment improvements, and mental health among Japanese employees from various industries. In this protocol, we demonstrate the study design and demographic data of the participants in the baseline survey. Invitations to participate in this study were sent to 421,825 internet monitor registrants in February 2022. Overall, 20,000 registrants who met the inclusion criteria participated in the survey. There were large variations in occupations and working styles (e.g., physical work, night work, and teleworking) among the participants, and we also found significant differences between male and female participants in the demographic data. An overview of the survey data suggests that the demographic characteristics of the participants in this study are comparable to those reported in previous studies on Japanese employees. We plan to use these survey data in the future to examine the associations of daily lifestyles and work environments with the mental health of Japanese employees.

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.

Impaired self-monitoring ability on reaction times of psychomotor vigilance task of nurses after a night shift.

The cognitive ability to self-monitor one's current performance is important for hospital nurses to maintain safety and health. However, studies on the effects of rotating shift work on self-monitoring ability are insufficient. We examined the differences in self-monitoring accuracy across shifts in a rotating three-shift system among 30 female ward nurses (mean age 28.2 years). Their self-monitoring ability was calculated by subtracting the predicted reaction times of the psychomotor vigilance task performed just before exiting the workplace from the actual reaction times. A mixed-effect model was employed to assess the effects of shift, awake hours, and prior sleep duration on self-monitoring ability. We observed impaired self-monitoring ability in nurses, particularly after the night shift. Although actual performance remained high across all shifts, their self-predictions on reaction times became pessimistic in the night shift, resulting in a difference of approximately-100 msec. The effect of the shift on self-monitoring was obvious even after adjusting for sleep duration and hours awake. Our findings indicate that the misalignment between their working hours and circadian rhythms may affect even professional nurses. Occupational management that emphasizes maintaining circadian rhythms will improve the safety and health of nurses.

Mediating and Moderating Effects of Psychological Detachment on the Association Between Stressors and Depression: A Longitudinal Study of Japanese Workers.

OBJECTIVES: This study examines the mediating and moderating effects of psychological detachment (PD) based on the stressor-detachment model in the long term. METHODS: Two waves of Web-based surveys, 28 months apart, yielded 3556 responses from Japanese workers. Comparisons between models that included mediating and moderating effects of PD and reverse direction mediating effects (strain → PD → stressor) were made by structural equation modeling. Differences in depression as a strain between combinations of high and low stressors and PD were also examined. RESULTS: The best-fitting model was the moderation/reciprocal partial-mediation model. The effect of PD was significant in the group with stable or decreasing stressor. CONCLUSION: According to the worker's level of stressors, PD, and depression, targeted interventions may effectively prevent physical and mental health problems caused by chronic stress.

Shift-Work Schedule Intervention for Extending Restart Breaks after Consecutive Night Shifts: A Non-randomized Controlled Cross-Over Study.

More knowledge is required to determine the optimal shiftwork schedule to reduce the harmful effects of short restart breaks between shifts. This 5-month intervention study aimed to examine the effectiveness of extended restart breaks from 31 h to 55 h after consecutive night shifts by considering the characteristics of the circadian rhythm to mitigate fatigue and sleep among 30 shift-working nurses. Subjective and objective variables, such as vital exhaustion, distress, hair cortisol, salivary C-reactive protein, and sleep mattress sensor sensation, were repeatedly measured to examine the differences between the intervention and control conditions. Two-way (condition × time) multilevel analyses showed significantly lower levels of vital exhaustion and distress in the intervention condition (p = 0.005 and p = 0.004, respectively). However, the expected benefit of the intervention was not observed in objectively measured variables. These findings suggested that an extended restart break after consecutive night shifts can moderately decrease occupational fatigue and stress.

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.

Conversation time and mental health during the COVID-19 pandemic: A web-based cross-sectional survey of Japanese employees.

OBJECTIVE: During the Coronavirus disease 2019 (COVID-19) pandemic, social isolation and impaired social interaction could be the factors that cause mental health problems. This study investigated the association between conversation time in daily life and mental health among Japanese employees. METHODS: In August 2021, a web-based cross-sectional survey was conducted with 1000 Japanese employees. Weekly conversation time was assessed in four domains (family members, friends, someone in the workplace, and others), and mental health was assessed using the Japanese version of the Kessler Psychological Distress Scale (K6 scale). Weekly total conversation time was calculated, and participants were assigned to one of the four conversation time categories based on quantile values to investigate the associations with poor mental health (K6 ≥ 13). RESULTS: The logistic regression analyses revealed that participants with short conversation times (<3.5 h per week) had poorer mental health compared to those with long conversation times (> 21.0 h per week), even after adjusting for confounders (OR = 2.48 [95% CI 1.31-4.71]). For the exploratory analyses of conversation time for each domain, the associations of short conversation time in the workplace with poor mental health was most robust (OR =2.02 [95% CI 1.13-3.63]). CONCLUSIONS: Japanese employees with conversation time of <3.5 h per week (i.e., 30 min per day) had poor mental health. During the COVID-19 pandemic, people have largely limited opportunities to have conversations with others, but a certain level of conversation time might be required to maintain mental health.

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.

[Characteristics of compensated mental disorders caused by overwork among drivers and non-drivers in the Japanese trucking industry].

OBJECTIVES: This study examined the characteristics of occupational mental disorders among those involved in the transport and postal activities in the trucking industry. METHOD: We examined 237 out of 3,517 cases of occupational mental disorders, compensated between the fiscal years 2010 and 2017. An assessment was made for sex, "life-or-death" status at compensation, age at the onset and suicide, the diagnosis according to the International Classification of Diseases, Tenth Revision, and other factors regarding occupational compensation. The participants were divided into two groups: truck drivers and non-truck drivers. RESULTS: Men accounted for approximately 90% of the cases. Depressive episode (F32) was the most common diagnosis in drivers and non-drivers, thus constituting 65 out of 149 and 48 out of 88 cases, respectively. The next most common type of mental disorder was adjustment disorders (F43.2), with 34 out of 149 drivers and 24 out of 88 non-drivers reporting them. Furthermore, the majority of drivers that had posttraumatic stress disorder (24 out of 27 cases) reported that they "suffered a serious illness or injury" and "experienced or witnessed a terrible accident or disaster." Occupational disasters due to long working hours were 52.4% for drivers and 73.9% for non-drivers. A total of 30.8% of the drivers reported working long hours since they joined the company. CONCLUSION: Drivers' long working hours entail waiting at the origin and cargo destination site, handling cargo, and incidental tasks other than driving. Thus, the reduction in work hours regarding these tasks needs to be a fundamental goal, and measures that include mental health care for accidents and miserable experiences must be implemented. However, long working hours for non-drivers are likely linked to job expansion/increase and reassignment/relocation. These findings highlight that to prevent overwork-related mental disorders, appropriate actions should be taken considering different sources of exposure for drivers or non-drivers.

[Examining the association between work-life factors and health disorders/excessive fatigue among Japanese truck drivers].

OBJECTIVES: Karoshi problems (overwork-related deaths and disorders caused by cerebrovascular and cardiovascular diseases) still occur in Japan. Truck drivers, who are in one of the riskiest occupations, are reported to show an increased prevalence of hypertension, obesity, hyperlipidemia, and diabetes, which are characteristic of Karoshi. Their health problems also include excessive fatigue. This cross-sectional study aimed to examine the association between work-life factors and health disorders/excessive fatigue among Japanese truck drivers. METHODS: We distributed a questionnaire regarding work hours, health status, lifestyle, burden of driving, and excessive fatigue to 5,410 truck drivers and collected a total of 1,947 responses, all from males. The association between work-life factors and health outcomes was evaluated by multivariable logistic regression analysis adjusted for age, drinking, and smoking status. RESULTS: The prevalence rates of obesity, hypertension, hyperlipidemia, diabetes, cardiovascular disease, cerebrovascular disease, and excessive fatigue were 22.2%, 19.3%, 8.5%, 5.6%, 2.5%, 0.7%, and 6.0%, respectively. Significant associations were observed for long-haul trips (two days or more) with obesity (adjusted odds ratio 1.5 [95% Confidence Interval 1.1-2.1]), local and night trips with hypertension (1.5 [1.0-2.2]), early morning awakening on workdays with obesity (1.5 [1.1-2.1]), being indoor-oriented on weekends with hypertension (1.5 [1.1-2.0]); and heavy burden of driving at night with hyperlipidemia (2.0 [1.3-3.0]). The adjusted odds ratios were significant for waking after sleep onset (2.6 [1.2-5.3]) and lack of sleep satisfaction (2.7 [1.4-5.1]) on workdays, less than six hours of sleep (2.8 [1.0-7.8]) and lack of sleep satisfaction (2.8 [1.5-5.2]) on weekends, 0-3 days off per month (3.6 [1.3-10.2]), and heavy burden of driving at night (2.2 [1.0-4.8]) with excessive fatigue. CONCLUSIONS: The present findings highlight that night and early morning work, heavy burden of night driving, and the resultant decreases in the quality and quantity of sleep may represent shared risk factors for health disorders and excessive fatigue among truck drivers. Adequate measures should be taken to limit the amount of night and early morning work, reduce the burden of night driving, and ensure days off for sleep opportunities and leisure activities, with the goal of preventing Karoshi.

Effects of work conditions and organisational strategies on nurses' mental health during the COVID-19 pandemic.

AIMS: This study aims to examine coronavirus disease 2019 (COVID-19) pandemic-related work factors for adverse effects on the mental health and whether organisational strategies attenuate these effects. BACKGROUND: COVID-19 pandemic has led to increased work burden and mental health risks for nurses. METHODS: A total of 1499 Taiwanese full-time nurses completed a web-based questionnaire between July and December 2020. Pandemic-related work conditions, namely, increased working hours, caring for COVID-19 patients, occupational stigma and redeployment, were assessed. Organisational strategies to combat pandemic-related work stressors including compensation to workers and adequate protection equipment were surveyed. Outcome measures were intention to leave, burnout and depression assessed using validated questionnaires. RESULTS: Redeployment, increased working hours and occupational stigma were associated with adverse mental health and intention to leave in logistic regression analysis. Caring for COVID-19 patients was negatively associated with depression. Adequate compensation for workers modified the association between redeployment and burnout. CONCLUSIONS: Pandemic-related work conditions were associated with adverse mental health and intention to leave. Organisational strategies attenuated the adverse impact of the pandemic. IMPLICATIONS FOR NURSING MANAGEMENT: Efforts to decrease stigma and organisational strategies including compensation for workers and adequate protection equipment provision should be adopted to improve nurses' health during a pandemic.

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.

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.

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.

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.

Trends in Work Conditions and Associations with Workers' Health in Recent 15 Years: The Role of Job Automation Probability.

Job automation and associated psychosocial hazards are emerging workplace challenges. This study examined the trends in work conditions and associations with workers' health over time in jobs with different automation probabilities. We utilized data from six waves of national questionnaire surveys of randomly selected 95,762 employees between 2001 and 2016. The Job Content Questionnaire, the Copenhagen Burnout Inventory, and the Self-Rated Health Scale were applied, and working time was self-reported. Automation probability was derived for 38 occupations and then categorized into three groups. Trends in work conditions and the associations between automation probability, work conditions and health were examined. We observed a 7% decrease in high automation probability jobs, an overall increase in job demands for and prevalence of shift work, and a decrease in job control. Workers with high automation probability jobs had low job demands, low job control and high job insecurity. Low automation probability was associated with burnout in logistic regression models. The odds ratio of job insecurity, long working hours, and shift work relating to health was higher in the later years of the surveys. In conclusion, there has been a decrease in high automation probability jobs. Workers employed in jobs with different levels of automation probability encountered different work condition challenges.