Association of onset of obesity with sleep duration and shift work among Japanese adults.

OBJECTIVE: The objective of this longitudinal epidemiological study was to investigate the association of risk factors for cardiovascular illness with sleep duration and shift work.

METHODS: This study used data obtained at medical checkups conducted in 1999 and 2006 for the employees of a local government organization in Japan (covering 21,693 male employees and 2109 female employees). The medical checkup data included (1) body measurements, (2) blood test parameters, and (3) replies to a self-administered questionnaire (inquiring about sleep duration, with or without shift work, etc.). On the basis of these data, we conducted multiple logistic regression analyses to study the association between the risk of new-onset obesity, hypertension, hyperglycemia, hypertriglyceridemia, and hypo-high density lipoprotein (HDL) cholesterolemia and shift work as well as sleep duration.

RESULTS: Among the male subjects who were engaged in shift work, the relative risk of new-onset obesity for those with a sleep duration of less than 5 h was 1.30 (95% CI, 1.14-1.49) higher than for those with sleep duration of 5-7 h. Furthermore, analysis using both engagement in shift work and sleep duration as dependent variables showed that the relative risks of new-onset obesity for those with a sleep duration of less than 5 h were 1.20 (95% CI, 1.09-1.32) for men and 1.7 (95% CI, 1.11-2.87) for women.

CONCLUSIONS: Short sleep duration is associated with onset of obesity.