Poor Sleep May Be Feeding the Obesity Crisis, Researchers Say

About 70% of teenagers and 30% of adults fail to get the recommended amount of sleep, and researchers say the shortfall may be doing more than affecting mood and grades -- it could be contributing to the obesity crisis. "People are increasingly recognizing that sleep is also an important aspect of weight management," said Stacey L. Simon, a sleep expert and professor of pediatrics at the University of Colorado Anschutz School of Medicine.

Repeated studies restricting adults' sleep have found they go on to eat between 200 and 300 extra calories, said Seth Creasy, an associate professor of endocrinology, metabolism and diabetes at CU Anschutz. Diet and physical activity remain the two main drivers of weight gain, he said, but sleep can support both. In one intervention, people who habitually slept less than six hours a night extended their sleep toward the recommended seven and a half hours over two weeks, and without being told to change their eating, ended up naturally eating about 270 fewer calories a day.

In adolescents, whose circadian rhythms naturally delay bedtime, short sleep duration and late sleep timing have been linked to poorer insulin sensitivity, which over time could raise the risk of obesity and type 2 diabetes, Simon said. The American Academy of Pediatrics recommended in 2014 that middle and high schools start no earlier than 8:30 a.m., but Simon said compliance has lagged.

Sleep deprivation has also been linked to higher levels of the hunger hormones leptin and ghrelin, leaving people hungrier and less satisfied after eating, and researchers say the brain's reward system responds to short sleep by seeking out food, especially high-sugar, high-fat food. Simon's research also found that adolescent females had earlier circadian timing than males, suggesting they may need more sleep, yet they report higher rates of insomnia.

It is harder to study how a lack of sleep affects the calories a person burns the next day, so fewer studies exist on that side of the equation than on eating patterns.