Sleep duration associated with body mass index among Chinese adults.

OBJECTIVE The objective of this study was to investigate the relationship between sleep duration and obesity among Chinese adults. METHODS A community-based cross-sectional study was conducted among Chinese adults in 2008. In total, 3225 participants were selected by a multistage cluster sampling method. Self-reported sleep duration was measured by a standardized questionnaire. Logistic regression models were used to estimate the odds ratios (ORs) (95% confidence intervals, CIs) of obesity with sleep duration, separated by gender, and adjusted for age, education, occupation, marriage, smoking, drinking, body pain, and health status. RESULTS The mean sleep duration was 7.8 h. Among the 2962 participants, 7.2% had short sleep duration (≤6 h/day). There were 171 obese participants (5.7%) in this population. After adjustment for age, short sleep duration (<6 h) was significantly associated with obesity among men (OR: 2.15; 95% CI: 1.193.90), but not among women; additional adjustment for potential confounders did not attenuate the association among men. Increasing sleep duration (a continuous variable) was significantly and negatively associated with obesity in women after adjustment for education level, occupation, marital status, smoking, drinking, body pain, and health status. The adjusted OR per-hour increase in sleep duration was 0.74 (0.56-0.97) for obesity, suggesting that for a 1-h increase in sleep duration among women, obesity risk decreased by 26%. CONCLUSION Short sleep duration was associated with increasing obesity in Chinese men, and sleep duration was associated with obesity in Chinese women, although the underlying mechanism is unclear. This possible gender difference warrants further studies.