Sleep duration is associated with body fat and muscle mass and waist-to-height ratio beyond conventional obesity parameters in Korean adolescent boys.

While evidence has supported a strong association between sleep duration and obesity globally, results from studies of children and adolescents have been conflicting, and information about a sex-specific association has been limited. This study aimed to investigate the association of sleep duration with various parameters of obesity among South Korean adolescents. This population-based, cross-sectional study analysed the data obtained from the Korea National Health and Nutrition Examination Surveys (KNHANES) 2009 and 2010. Data of 990 adolescents were analysed. Sleep duration was based on a self-reported questionnaire. Body mass index (BMI), waist circumference (WC), waist-to-height ratio (WHtR), body fat percentage (BFP) and skeletal muscle index (SMI, appendicular skeletal muscle mass as a percentage of body weight) were assessed as parameters of obesity. Mean sleep duration in boys was associated inversely with BMI, WC, WHtR and BFP and positively with SMI. Proportions of the highest quartile of BMI, WC, WHtR and BFP and the lowest quartile of SMI increased significantly with increased sleep duration only in boys. Also, in boys, decreased sleep duration was associated significantly with the increased risk of the highest quartile of BMI, WC, WHtR and BFP and the lowest quartile of SMI, even after adjusting for confounding factors. However, in girls, there was no significant association between sleep duration and obesity parameters except WC. Periodic assessment of sleep duration in relation to body fat or muscle mass in male adolescents may be considered, especially in those who are at risk for obesity or related disorders.