Long working hours and obesity with special reference to sleep duration.

concluding that overtime work has a relationship with short sleep duration (<6 hours/day) even at 26 hours/ month. Virtanen et al. reported a cross-sectional study and two longitudinal studies that examined the relationship between long working hours and short sleep duration. A significant odds ratio for short sleep duration (<7 hours/day) was observed in a case-control study when weekly working hours exceeded 40 hours. In addition, a longer follow-up study with a duration of more than 5 years also presented a significant odds ratio for short sleep duration for the same number of working hours. Hammer and Sauter reported that work-life stress is related to poor health behaviors, including smoking, drinking, low levels of exercise and even decreased sleep duration, and that sleep factors are important for maintaining a good work environment. Overtime work is considered to be an important risk factor of cardiovascular disease (CVD), and obesity is also a fundamental risk factor of CVD in relation to metabolic syndrome. Jang et al. conducted a crosssectional study to examine the association between work hours and obesity and further study is recommended to speculate about the causality of the association between long work hours and obesity in the form of a follow-up study that considers gender and type of job as confounders.