Here's yet another possible explanation for why sleep may be associated with weight gain and obesity -- a small new study shows that not getting enough Zzzs can spur people to opt for bigger portion sizes.
The study, published in the journal Psychoneuroendocrinology, included 16 men of normal weight who were asked to pick how much food they wanted from a buffet-like presentation of meals and snacks. They were asked to do this once after having had eight hours of sleep (a full night's rest), and then again after a night of being deprived of sleep. Researchers also examined the portion sizes chosen by the study participants before eating breakfast and after eating breakfast.
Researchers found that when the men were sleep-deprived, they chose bigger portions of food than when they had a full night's rest. They also reported feeling hungrier, and had increased blood levels of the hunger-stimulating hormone, ghrelin.
After eating breakfast, researchers found that the sleep-deprived study participants wanted bigger snack portions than pre-breakfast. However, they still chose the same meal portion sizes post-breakfast as they did post-breakfast.
This suggests "that sleep deprivation enhances food intake regardless of satiety," study researcher Pleunie Hogenkamp, of Uppsala University, said in a statement. "Bearing in mind that insufficient sleep is a growing problem in modern society, our results may explain why poor sleep habits can affect people's risk to gain weight in the long run."
Past studies have also shown a link between sleep deprivation and important bodily processes, like blood glucose metabolism and blood pressure control. And getting fewer than six hours of sleep a night could also spur increases in ghrelin and decrease insulin sensitivity, other research has shown.