Association Between Sleep Duration, Quality and Body Mass Index in the Korean Population

Study Objectives: Mounting evidence indicates that sleep disturbance contributes to the increased risk for cardiometabolic diseases. Obesity and underweight are also closely linked to cardiometabolic risk. Thus, the objective of this study was to examine the association between sleep duration, quality, and body mass index (BMI) categories. Methods: Using data from a cohort of 107,718 Korean individuals (63,421 men and 44,297 women), we conducted cross-sectional analysis with sex subgroup analysis. Sleep duration was classified into 3 groups-short (< 7 hours), normal (7-9 hours) and long sleep (> 9 hours)-and Pittsburgh Sleep Quality Index (PSQI) score was used to divide sleep quality into 2 groups-poor (PSQI 5) and good sleep (PSQI <= 5). Compared to normal sleep and good sleep quality, adjusted odds ratios of short and long sleep and poor sleep for BMI categories were calculated. BMI categories included underweight (BMI < 18.5 kg/m(2)), overweight (BMI 23 to < 25 kg/m(2)), obesity (BMI 25 to < 30 kg/m(2)) and severe obesity (BMI 30 kg/m(2)). Results: Short sleep duration had the dose-dependent relationship with obesity categories from overweight to severe obesity, and inverse relationship with underweight (adjusted odds ratios [95% confidence intervals] for underweight, overweight, obesity, and severe obesity versus normal weight; 0.88 [0.82-0.94], 1.15 [1.11-1.20],1.31 [1.26-1.37], 1.70 [1.54-1.85]). Poor sleep quality was significantly associated with severe obesity in male subgroup (1.16 [1.05-1.27]) and with obesity (1.18 [1.10-1.25]) and severe obesity in female subgroup (1.66 [1.40-1.98]). Conclusions: Short sleep duration and poor sleep quality was more positively associated with obesity across BMI than underweight.