GHRL and Insulin resistance: Many studies have found that cortisol levels elevated in the afternoon and evening, and the magnitude of these increases may be related to insulin resistance.24,30 Moreover, the lack of sleep causes a satiety hormone (leptin) to decrease, an appetite-stimulating hormone (ghrelin) to increase, resulting in increase in hunger and food intake,31 which may eventually be related to an increased risk of T2DM.