a dose-response relationship between short sleep duration and high BMI has been reported in different age groups. In the largest study, elevated BMI values were observed for habitual sleep lasting less than 7 to 8 hours per day. A U-shaped curvilinear relationship between sleep duration and BMI has been reported in women. However, in men, there seemed to be a monotonic trend toward higher BMI with shorter sleep duration. Importantly, a recent prospective study identified a longitudinal association between short sleep duration and subsequent weight gain