According to Harvard Medical School, a few studies have found a link between lack of sleep and weight gain. Along with eating too much and not exercising, sleep deprivation is one of the risk factors for obesity.
Sleep deprivation increases production of the stress hormone cortisol. Lack of sleep lowers your levels of a hormone called leptin, which tells your brain that you’ve had enough to eat. In addition, it raises levels of a biochemical called ghrelin, which is an appetite stimulant.
Sleep deprivation prompts your body to release higher levels of insulin after you eat, promoting fat storage and increasing your risk of developing type 2 diabetes.