If people don’t get enough sleep, they may also eat too much—and thus be more likely to become obese. That is the finding of researchers who presented their study at the American Heart Association’s Epidemiology and Prevention/Nutrition, Physical Activity and Metabolism 2012 Scientific Sessions.

"We tested whether lack of sleep altered the levels of the hormones leptin and ghrelin, increased the amount of food people ate, and affected energy burned through activity," said Virend Somers, MD, PhD, study author and professor of medicine and cardiovascular disease at the Mayo Clinic, Rochester, Minn.

The researchers studied 17 normal, healthy young men and women for 8 nights, with half of the participants sleeping normally and half sleeping only two-thirds their normal time.

Participants ate as much as they wanted during the study.

Researchers found:
• The sleep deprived group, who slept 1 hour and 20 minutes less than the control group each day, consumed an average 549 additional calories each day.
• The amount of energy used for activity didn’t significantly change between groups, suggesting that those who slept less didn’t burn additional calories.
• Lack of sleep was associated with increased leptin levels and decreasing ghrelin—changes that were more likely a consequence, rather than a cause, of overeating.

The researchers noted that while this study suggests sleep deprivation may be an important part and one preventable cause of weight gain and obesity, it was a small study conducted in a hospital’s clinical research unit.