Do you get the munchies in the middle of the night? It might be biology. Researchers at Oregon Health & Science University and their colleagues at Harvard have discovered that an internal circadian rhythm may be responsible for increased hunger and craving for high-calorie food in the evenings and late night.
Controlling for other factors that can affect hunger, the team found that participants in the study felt the least hungry in the morning (8 a.m.) and most hungry in the evening (8 p.m.). Similar rhythms were found in a desire for foods that were sweet, starchy and salty. The study concluded that an internal circadian rhythm causes an evening peak in appetite that may promote larger, higher-calorie meals before the fasting period necessitated by sleep. “From an evolutionary perspective,” says Steven A. Shea, Ph.D., Director of the Center for Research on Occupational and Environmental Toxicology at OHSU and senior author on the study, “it was probably useful – particularly in times of food shortage – to increase food intake in the evening before sleep, to help recover from the activities of the day, rejuvenate the body and lay down energy stores for the exertions of the next day.”