Mental health effects of long work hours, night and weekend work, and short rest periods

Although the prior literature has examined the relationship between work schedule characteristics and worker mental health, establishing the causal effect of work schedule characteristics is challenging because of endogeneity issues. This paper investigates how various work schedule characteristics affect workers' mental health using employee surveys and actual working hours recorded over seventeen months in a Japanese manufacturing company. Our sample includes 1334 white-collar workers and 786 blue-collar workers observed from 2015 to 2016. Our major findings are as follows: long working hours cause the mental health of white-collar workers to deteriorate even after controlling for individual fixed effects. Furthermore, working on weekends is associated with mental ill health—the negative effect of an hour increase in weekend work is one and a half to two times larger than that of weekday overtime work for white-collar workers. On the other hand, short rest periods are not associated with mental health for them. Our results indicate that taking a relatively long rest period on weekends is more important for keeping white-collar workers healthy than ensuring a sufficient daily rest period. Regarding blue-collar workers, our analysis reveals that working after midnight is associated with mental ill health, whereas short rest periods are not associated with their mental health. This suggests that the strain of night work is a more important determinant of mental health for blue-collar workers. The differences in the relationship between work schedule characteristics and workers’ mental health for white-collar and blue-collar workers can be explained in terms of different work styles, different expectations, and different degrees of selection. We conclude that working for long hours or irregular hours deteriorates the mental health of workers but its impact is likely to differ significantly across job types.