Too little sleep may contribute to a larger waistline, researchers say.
Higher fat intake
The new research included 11 studies with a total of 172 participants. Compared to those who got enough sleep, those who were sleep-deprived consumed an average of 385 more calories a day. That's equal to the calories in about four and a half slices of bread.
Sleep deprivation didn't have a significant effect on how many calories people burned. That means those with sleep deprivation had a net gain of 385 calories a day, the researchers said.
Read: Sleep vs. no sleep
People with too little sleep had higher fat and lower protein intake than those who got enough sleep, but both groups had similar carbohydrate intake.
The paper was published in the European Journal of Clinical Nutrition.
Chronic sleep loss
"The main cause of obesity is an imbalance between calorie intake and expenditure and this study adds to accumulating evidence that sleep deprivation could contribute to this imbalance. So there may be some truth in the saying 'early to bed, early to rise, makes a man healthy and wise'," said senior study author Gerda Pot. She's with the diabetes and nutritional sciences division at King's College London and Vrije Universiteit in Amsterdam.
Read: Sweet sleep
If sleep deprivation lasts long-term, an extra 385 calories a day would likely contribute to weight gain, Pot added.
"Reduced sleep is one of the most common and potentially modifiable health risks in today's society in which chronic sleep loss is becoming more common. More research is needed to investigate the importance of long-term, partial sleep deprivation as a risk factor for obesity and whether sleep extension could play a role in obesity prevention," Pot concluded.
A previous study found that partial sleep deprivation led to greater activation of brain areas associated with reward when people were exposed to food.