Association between sleep duration and metabolic syndrome: a cross-sectional study

Background: Both short and long sleep duration have been consistently studied as a risk factor for obesity, hyperglycemia and hypertension. In this cross-sectional study, we provide an updated analysis of the Health Examinees (HEXA) study on the association between sleep duration and metabolic syndrome (MetS) occurrence among Koreans age 40-69 year olds. Methods: A total of 133,608 subjects (44,930 men, 88,678 women) were enrolled in the HEXA study 2004-2013. Sleep duration was categorized into 4 sleep categories (< 6 h, 6 to < 8 h, 8 to <10 h, >= 10 h). MetS criterion was based on the National Cholesterol Education Program, Adult Treatment Panel III. Logistic regression was used to calculate adjusted odds ratios (ORs) and 95% confidence intervals (CIs). Results: Compared with individuals sleeping 6 to < 8 h per day, less than 6 h of sleep was associated with MetS (multivariable adjusted OR: 1.12, 95% CI: 1.05-1.19) and elevated waist circumference (1.15, 1.08-1.23) among men; with elevated waist circumference (1.09, 1.04-1.14) among women. Greater than 10 h of sleep was associated with MetS (1.28, 1.08-1.50) and elevated triglycerides (1.33, 1.14-1.56) among men; with MetS (1.40, 124-1.58), elevated waist circumference (1.14, 1.02-1.27), elevated triglycerides (1.41, 1.25-1.58), reduced high-density lipoprotein cholesterol (HDL-C) (1.24, 1.12-138), and elevated fasting glucose (1.39, 1.23-1.57) among women. Conclusions: Less than 6 h of sleep is associated with elevated waist circumference among both men and women and with MetS among men only. Greater than 10 h of sleep is associated with MetS and elevated triglycerides among both men and women and with elevated waist circumference, reduced HDL-C, and elevated fasting glucose among women only.