Associations of employment status, working time and job satisfaction with sleep duration and sleep quality among the 50+ population in Japan.

Few studies have addressed the relationship between sleep and employment in Japan. We use four waves of the Japan Study of Aging and Retirement (JSTAR) to address the relationship between weekday sleep duration, self-reported sleep quality and four self-reported indicators of sleep quality and employment status (model 1, full sample), working hours and job satisfaction (model 2, working sample) among individuals aged 50 and over (N=7,082). We apply mixed effects models for the linear outcome of sleep duration and cumulative link mixed models for the sleep quality variables, controlling for socio-demographic and health characteristics. In model 1, our findings show that, compared to full-time employees, all categories of workers and non-workers report longer sleep hours. Some sub-groups, such as contract workers, report higher odds of waking up at night or in the early morning, and taking a longer time to fall asleep. In model 2, we find a positive association between working time and sleep hours but including job satisfaction in the model absorbs such a relationship, indicating the job satisfaction somehow reflects working time. Poor job satisfaction is linked to higher odds of experiencing difficulties in four of the five sleep quality measures.