Science has been pretty strong on connecting sleep deprivation to weight gain. Now a new study from UC Berkeley shows one reason might lie in the brain and how it is affected by sleep deprivation.
While the study was small -- 23 people -- it's certainly intriguing. The recruits were monitored for two individual nights, a week apart. On one night, they got a normal night's sleep (they slept 8.2 hours on average). On the other night, they were not allowed to sleep at all. After they had not slept, the study participants showed a much stronger preference for high-calorie foods, such as pizza and doughnuts, over more healthful choices like strawberries and carrots.
In addition, researchers, led by Matthew Walker, a UC Berkeley psychology professor, measured areas of the brain using functional magnetic resonance imaging. The preference for high-calorie foods among the sleep-deprived matched with greater activity in an area of the brain called the amygdala, which the authors say has been "strongly implicated in governing the motivation to eat." At the same time, those who were sleep-deprived had "significantly reduced activity" in three areas of the brain that have to deal with decision-making.
In other words, it's a double whammy: The sleep-deprived subjects wanted higher-calorie foods and had impaired rational decision-making to overcome those urges.
"This combination of altered brain activity and decision-making may help explain why people who sleep less also tend to be overweight or obese," said Walker in a release.