Longitudinal association between nonstandard work schedule and depressive symptoms

Abstract Background Nonstandard work schedules (NSWSs) have been linked to increased risk of depression, but the evidence is mostly from cross-sectional studies and data on the risk distribution across various groups is lacking. We examined the impact of different NSWSs on depressive symptoms and assessed effect modification by sex, ethnicity, and immigrant status. Methods We used five waves of longitudinal data from the Understanding Society, the UK Household Longitudinal Study, which were collected biennially from 2010/11 to 2018/19. The study sample comprised 11371 employed workers aged 16 to 58 years in 2010/11. Generalised estimating equation with logistic regression was used to assess crude and adjusted effects of NSWS types (work time arrangement, work hours, and weekend working) on depressive symptoms. Independent correlation was specified in all the models. Complete-case and multiple imputation analyses were performed. Results After adjusting for confounders, only weekend work was associated with depressive symptoms. Workers who worked most/all (OR 1.24; 95%CI 1.13 - 1.37) or some (OR 1.10; 95%CI 1.02 - 1.18) weekends had a higher risk of depressive symptoms than workers who did not work on weekends. Ethnicity modified the association between work hours and depressive symptoms, indicating a higher risk among White workers working > 40 hours/week (OR 1.10; 95%CI 1.02 - 1.20) and Asian workers working <35 hours/week (OR 1.72; 95%CI 1.32 - 2.25) compared to White workers working 35-40 hours/week. No effect modification by sex or immigrant status was observed. The results were the same as those obtained from the imputation model. Conclusions Weekend work, long work hours (for White workers), or working < 35 hours/week (for Asian workers) were associated with increased risk of depressive symptoms. These findings indicate the need to review the working conditions of workers exposed to NSWSs, especially those working on weekends and Asian workers who work part-time. Key messages • Weekend work schedule is associated with an increased risk of depressive symptoms among employed workers in the UK. • The effect of work hours on depressive symptoms varies by ethnicity.