Basic attributes and lifestyle habits

Occupational position was categorized into 2 groups: managers or non-managers. This was assessed with the question “Are you in managerial position or not?”, with the answer options “yes” or “no.” In this study, we defined managers as workers who thought they were in managerial position. The questionnaires also asked about basic demographic characteristics, such as age, sex, marital status (single, married or divorced/bereaved), having children (yes or no), parents living together (father or mother), job type (researcher/academic, technician/engineer, clerk/ administration or others), household income (<4 million yen, 4–8 million yen, 8–12 million yen, and ≥12 million yen), employment status (part-time/temporary, full-time [fixed-term] or full-time [permanent]), exercise habit (less than once a month, several times a month, once a week, or more than once a week), and smoking status (yes, past, or no). It is reported that mental health of women have association with family status including household income.^20,21 The covariates of marital status, having children, parents living together and household income were included to test the hypothesis that female workers who were unmarried, have children, or have low household income, were at greater risk of poor mental health. It is also reported that occupational status affected mental health of workers²²; thus, job type was set as a covariant. Additionally, exercise habit and smoking status were reported to associate with mental health.^23-25 Therefore, we formed a hypothesis that female workers who take little exercise or smoke were in poor mental health, and we included them as co-variants.