Previous research has shown links between sleep deprivation and increased appetites, but a recent UC Berkeley study now illuminates how poor sleep affects our food cravings — and the brain mechanisms behind it all.
Using fMRI scans, researchers analyzed the brain activity of 23 healthy young adults — initially after a normal night's sleep and then after a night of no sleep. Participants were more likely to crave junk food like burgers, pizza and doughnuts following the sleepless night, and the brain scans indicated two important changes in brain activity: Activity in the sleep-deprived brain's frontal lobe — the part of the brain responsible for complex decision-making — was impaired, but researchers noticed there was increased activity in deeper brain centers that respond to rewards.
“What we have discovered is that high-level brain regions required for complex judgments and decisions become blunted by a lack of sleep, while more primal brain structures that control motivation and desire are amplified,” said Matthew Walker, a UC Berkeley professor of psychology and neuroscience and senior author of the study.
In the study, which was published Tuesday in the journal Nature Communications, participants viewed a series of 80 food images illustrating everything from healthy options — such as strawberries, apples and carrots — to high-calorie junk food, such as burgers and pizza. They rated their cravings for each food and were provided with the food they craved the most after the brain scan.
They were significantly less likely to choose whole grains and leafy vegetables after the sleepless night, instead craving the less healthy snacks and junk food.
“These results shed light on how the brain becomes impaired by sleep deprivation, leading to the selection of more unhealthy foods and, ultimately, higher rates of obesity,” said Stephanie Greer, a doctoral student in Walker’s Sleep and Neuroimaging Laboratory and lead author of the paper.