Association between sleep duration and metabolic syndrome: a population-based study in China

Introduction: The relationship between sleep duration and metabolic syndrome (MetS) remains debatable. In the present study, we analysed the link between total sleep duration (including nighttime sleep and nap duration) and MetS as well as its components among the Chinese population. Material and methods: This was a cross-sectional study from a prospective population cohort including 8616 participants over 40 years in Guangxi, China, evaluated from April 2011 to January 2012. MetS was diagnosed using modified criteria from the National Cholesterol Education Program’s Adult Treatment Panel III. Sleep information was obtained through a standard self-report-based questionnaire. The connection between sleep duration and MetS prevalence as well as its components was evaluated using a logistic regression model. Results: After adjusting for potential confoundings, the longer daily sleep duration (≥ 10 hours) group was observed to have the higher odds of having MetS than the reference group with ≥ 7 and < 8 hours of sleep [odds ratio (OR): 1.25, 95% confidence interval (CI): 1.03–1.52, p = 0.023], as well as the highest odds of having elevated triglycerides (OR: 1.25, 95% CI: 1.03–1.52) and fasting blood glucose (OR: 1.21, 95% CI: 1.01–1.45). Further analysis demonstrated that sleeping > 9 hours per night was correlated to MetS in females (OR: 1.27, 95% CI: 1.02–1.58), while napping ≥ 90 minutes was correlated to MetS (OR: 1.44, 95% CI: 1.11–1.87) in males. Conclusion: Both longer nighttime sleep duration and longer naps may be associated with the development of MetS