One meta - analysis of nearly 700 published studies showed that both adults and children who are short sleepers have an increased risk of obesity.1 In a different study, 12 men were allowed a full night of sleep (8 hours) followed by a partial night of sleep (4 hours); after the latter, the men were
hungrier upon waking up and ate more during the day (22 %).2 Acute partial sleep leads to increased serum levels of ghrelin (a hunger hormone) and decreased levels of leptin (a satiety hormone).