This study leverages a large sample from the Beijing Child and Adolescent Metabolic Syndrome (BCAMS) study[22] in order to test the hypothesis that sleep duration in childhood not only modifies the genetic predisposition to childhood obesity, but also has long term impact on obesity risk, as assessed at a ten-year follow-up, particularly for loci operating via the leptin pathway. The gene discussed is LEP; the disease is obesity due to melanocortin 4 receptor deficiency.