Associations Between Nonstandard Work Schedules and Abnormal Sleep Duration and Weekend Catch‐Up Sleep: Findings From a Nationally Representative Sample of Middle‐Aged Workers in Japan

BACKGROUND: Owing to the rise of the 24/7 economy, many workers operate around the clock. However, few studies have explored the association between specific types of nonstandard work schedules (NWSs) and sleep. METHODS: Using a nationally representative sample of middle-aged workers (n = 14,675) in Japan, we investigated the associations between four types of NWSs (evening, morning, both morning and evening, and night schedules) and abnormal sleep duration on weekdays and weekend catch-up sleep (WCS) via multinomial logistic regression. RESULTS: Compared to daytime work schedules, all four types of NWSs were associated with increased risks of very short (< 5 h) and long (≥ 9 h) sleep duration and short (1 h) WCS. Night schedules were associated with the highest risk of very short sleep duration, whereas both morning and evening schedules were associated with the highest risk of short (5 h) and long sleep duration. Additionally, both morning and evening, and night schedules were associated with increased risks of moderate (2 h) and long (≥ 3 h) WCS. Stratification revealed sex-related differences. CONCLUSIONS: Work timing is independently associated with abnormal sleep duration and WCS. Furthermore, the associations differ across different types of NWSs. These findings provide insights into worktime arrangements in workplaces to promote sleep health.