Association between weight gain, obesity, and sleep duration: a large-scale 3-year cohort study

Previous research suggests that sleep duration is associated with obesity and weight gain. However, the majority of these studies are of cross-sectional design, with only a few cohort studies. In order to validate previous findings in a more real-world context, we evaluated the association between sleep duration, obesity, and weight gain in a large, 3-year cohort study. A retrospective cohort study was conducted involving 21,469 apparently healthy individuals aged 20 years or older who underwent annual health check-ups at the Center for Preventive Medicine, St. Luke's International Hospital, between 2005 and 2008. The participants were divided into four groups according to their self-reported average nightly sleep duration (a parts per thousand currency sign5, 6, 7, and a parts per thousand yen8 h). We identified individuals with obesity (body mass index a parts per thousand yen25 kg/m(2)) and weight gain. Multivariate linear regression analysis and logistic regression analysis were used to explore the association between these variables and sleep duration, adjusting for age, gender, alcohol consumption, current smoking, past medical history, and level of physical activity. Compared with those who slept 7 h, the individuals who slept a parts per thousand currency sign5 h night were more likely to experience weight gain (beta coefficient = 0.03; 95% CI = 0.03-1.1) and to become obese (OR = 1.5; 95% CI = 1.1-2.0). No significant difference was seen between subjects who slept more than 8 h and those sleeping 7 h (OR = 1.3; 95% CI = 0.9-1.8). Short sleep (a parts per thousand currency sign5 h) is significantly associated with weight gain and obesity in both male and female adults.