Work intervals and the prevalence of depressive symptoms among daytime workers: Japan Epidemiology Collaboration on Occupational Health Study

OBJECTIVES: This study examined the association between work intervals and depressive symptoms among daytime workers, and whether lifestyle behaviors might help explain this association. METHODS: A cross-sectional analysis was conducted on 8007 daytime workers who participated in a questionnaire survey of the Japan Epidemiology Collaboration on Occupational Health Study. Work intervals-both including and excluding commuting time-were calculated based on the participants' self-reported work departure and arrival times. Depressive symptoms were assessed using the 11-item Center for Epidemiological Studies Depression Scale. Multilevel robust Poisson regression models were used to estimate the prevalence ratio (PR) and 95% confidence interval (CI) for depressive symptoms across work interval categories. Five lifestyle factors (sleep duration, breakfast consumption, dietary balance, dinner timing, and leisure-time physical activity) were examined in a mediation analysis to assess the extent to which they account for the observed association. RESULTS: The adjusted PRs (95% CIs) for depressive symptoms were 1.41 (1.12-1.77), 1.23 (1.12-1.35), 1.03 (0.96-1.11), 1.00 (reference), and 1.08 (1.04-1.12) for those with work intervals of