Some of lifestyle factors may influence sleep quality. Because poor sleep quality is associated with an increased risk for various physical and mental diseases, it would be beneficial to identify lifestyle factors that may lead to poor sleep quality.

The subjects were 3341 employees (2280 males and 1061 females) aged 20-65 in local government in Japan. A questionnaire survey was conducted in January 2003. Sleep quality was evaluated using Pittsburgh Sleep Quality Index (PSQI). PSQI consists of 7 subscale scores generating a global PSQI score. In the present study, a subject with a global score of more than 5.5 was defined as having poor sleep quality. Logistic regression analysis was conducted to evaluate whether smoking, exercise, and alcohol drinking habits were independently associated with poor sleep quality, after adjustment for potential confounding factors.

In both men and women, current smokers were more likely to have poor sleep quality. While, in men, physical inactivity (exercise frequency of less than 1/week) were associated with poor sleep quality, there were no significant relationship between physical inactivity and poor sleep quality in women. While, in men, daily alcohol drinking was associated with better sleep quality, no significant associations of drinking frequency with sleep quality were found in women.

Current smoking may lead to poor sleep quality for both men and women, while the associations of physical inactivity and infrequent alcohol drinking with poor sleep quality were significant only for men. Longitudinal study is necessary to confirm the causality.