U-shaped relationships between sleep duration and metabolic syndrome and metabolic syndrome components in males: a prospective cohort study

Objective: Based on cross-sectional studies, sleep duration has been shown to have a relationship with the prevalence of metabolic syndrome (MS); however, no prospective studies have verified a correlation between the incidence of MS and the gender difference. Herein we prospectively determined the association between MS and gender using a large sample. Methods: A total of 4774 subjects without MS, 30-65 years of age, participated in this study. One-way ANOVA and Chi-square test were used to analyze the baseline variables. Cox regression models were performed separately in a mixed-gender population, males and females, while controlling for lifestyle and sleep-related factors. Results: During an average of 4.4-year follow-up, 1506 subjects developed MS. Both short (<6 h) and long sleep durations (8-9 and >= 9 h) increased the incidence of MS and elevated the fasting blood glucose (FBG) level in the mixed-gender population (MS: HR = 1.43, 1.25, and 1.45, respectively; elevated FBG: HR = 1.61, 1.65, and 1.98, respectively) and males (MS: HR = 1.87, 1.73, and 1.96, respectively; elevated FBG: HR = 2.27, 2.28, and 3.16, respectively). The HR8-9 and >= 9 h for hypertriglyceridemia in males was 1.48 and 19.4, and the HR<6, 6-7, and >= 9 h for hypertension in females was 1.25, 1.46, and 1.72, respectively. Conclusion: Both short and long sleep durations were associated with a greater incidence of MS and elevated FBG in a mixed-gender population and in males, and hypertension in females. Males who sleep longer were also at a higher risk for hypertriglyceridemia. (C) 2015 Elsevier B.V. All rights reserved.