Correlation between shift-work-related sleep problems and heavy drinking in Japanese male factory workers.

AIMS To investigate the effects of shift work on increased alcohol intake associated with poor sleep quality. METHODS This cross-sectional survey evaluated the correlation between work schedule, poor sleep quality and heavy drinking among 909 factory workers aged 35-54 years in Japan. Subjects included 530 day workers, 72 shift workers who did not work at night and 290 shift workers who engaged in night work. Heavy drinking was defined as a mean volume of alcohol consumption exceeding 60 g/day. RESULTS Compared with other workers, night-shift workers who suffered poor sleep quality exhibited the highest frequency of heavy drinking (17.6%). Multiple logistic regression analysis demonstrated that compared with day workers with good sleep, night-shift workers who experienced poor sleep had more than twice the odds of heavy alcohol consumption (odds ratio 2.17 [95% confidence interval (CI), 1.20-3.93]). Shift workers who did not work at night and day workers with poor sleep were not at increased odds of heavy drinking. CONCLUSION Shift workers who engage in night work may try to modify their health behavior to cope with sleep problems. Such modification may be a risk factor for heavy drinking.