A cross-sectional study of the association between working hours and sleep duration among the Japanese working population

Objectives: This study aimed to clarify the association between long working hours and short sleep duration among Japanese workers. Methods: We selected 4,000 households from across Japan by stratified random sampling and conducted an interview survey of a total of 662 participants (372 men; 290 women) in November 2009. Logistic regression analyses were performed using "sleep duration < 6 hours per day" as a dependent variable to examine the association between working hours/overtime hours and short sleep duration. Results: When male participants who worked for ≥ 7 but < 9 hours per day were used as a reference, the odds ratio (OR) for short sleep duration in those who worked for ≥ 11 hours was 8.62 (95% confidence interval [CI]: 3.94-18.86). With regard to overtime hours among men, when participants without overtime were used as a reference, the OR for those whose period of overtime was ≥ 3 hours but < 4 hours was 3.59 (95% CI: 1.42-9.08). For both men and women, those with long weekday working hours tended to have a short sleep Durationduration during weekdays and holidays. Conclusions: It is essential to avoid working long hours in order to prevent short sleep duration.