Long working hours has been shown to have harmful effects on human health in previous
studies. The 2007 International Labour Organization (ILO) report2) 3 estimated that worldwide,
4 approximately 22.0% of workers worked more than 48 hours per week. This report also showed
5 that in 2004–5, 17.7% of workers in Japan worked ≥49 hours per week. In 2010, this proportion
increased to 23.1%, and it was 21.7% in 20133) 6 . Regarding the association between long working
hours and health, a recent systematic review1) 7 indicated that there is a robust association between
8 long working hours and coronary heart disease, depressive state, anxiety, and sleep problems.