Can psychosocial working conditions help to explain the impact of shiftwork on health in male- and female-dominated occupations? A prospective cohort study.

Occupational factors are sometimes invoked to explain gender differences in the associations between shiftwork and health. We examined prospective associations between shiftwork and health, and between shiftwork and sick leave, separately for workers in female-dominated (FD) and male-dominated (MD) occupations; and whether the associations remained after controlling for psychosocial working conditions. Data from six waves of the Swedish Longitudinal Occupational Survey of Health were used to examine prospective associations with a four-year time lag between work schedule (daywork versus shiftwork involving nightwork; and daywork versus shiftwork not involving nightwork) and self-reports of depressive symptoms; incidents of short- and long-term sick leave; self-rated health; and sleep disturbance. Dynamic panel models with fixed effects were applied, using structural equation modeling. The analyses included adjustments for personal circumstances and employment conditions; and additional adjustments for psychosocial working conditions (psychological and emotional job demands; job control; worktime control; social support at work; persecution at work; and threats or violence at work). Within FD occupations, shiftwork that included night work (as compared to daytime work) predicted higher incidence of short-term sick leave (<1 week); within MD occupations, shiftwork that included nightwork predicted greater symptoms of mild depression. Despite notable differences in psychosocial working conditions between dayworkers and shiftworkers, both associations remained significant after adjustments. Thus, it was not confirmed that the associations between shiftwork and health reflected poorer working conditions of shiftworkers in either FD or MD occupations, although the possibility remains that the associations were due to other unmeasured aspects of the working environment.