Dose-response association between sleep duration and obesity risk: a systematic review and meta-analysis of prospective cohort studies.

The association between sleep duration and obesity risk remains unclear. We performed an updated meta-analysis to quantify a potential dose-response relation between sleep duration and risk of obesity. PubMed and Embase were searched for prospective cohort studies examining the association between sleep duration and risk of obesity that were published up to October 28, 2017. Random effects models were used to evaluate the pooled relative risks (RRs) and 95% confidence intervals (CIs) for the association of sleep duration and obesity. Restricted cubic splines were used to model the dose-response association. The meta-analysis included 12 studies (16 reports). We found a reverse J-shaped relation between sleep duration and obesity, with the lowest risk at 7-8-h sleep per day. Compared with 7-h sleep duration per day, the pooled relative risks for obesity were 1.09 (95% CI 1.05-1.14) for each 1-h decrement among individuals who slept < 7 h per day and 1.02 (95% CI 0.99-1.05) for each 1-h increment of sleep duration among individuals with longer sleep duration. Short sleep duration significantly increased the risk of obesity. Compared with 7-h sleep duration per day, the risk of obesity increases 9% for each 1-h decrease in sleep duration.