Researchers Link Poor Sleep to Junk Food Cravings

A new study from the University of California, Berkeley suggests that sleep deprivation is linked to junk food cravings.

For the study, the brains of 23 healthy young adults were scanned using functional magnetic resonance imaging (fMRI) before a full, normal night's sleep and again after a sleepless night. Upon the second test, researchers found impaired activity in the sleep-deprived brain's frontal lobe, the part of the brain that governs complex decision-making. Moreover, the sleep-deprived people showed increased brain activity in deep brain regions linked with rewards and favored more unhealthy snacks and junk food when they were deprived of sleep.

"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, which was published Tuesday in the journal Nature Communications.

Walker also added that "high-calorie foods also became significantly more desirable when participants were sleep-deprived. This combination of altered brain activity and decision-making may help explain why people who sleep less also tend to be overweight or obese."

Poor sleep has previously been linked to larger appetites greater appetites and particular cravings for sweet and salty foods, but Walker said the latest findings provide a specific brain mechanism that can help explain why some people make poor food choices after a night of poor sleep.

"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.

For their study, the researchers measured brain activity as participants were asked to view and rate their desire for a series of 80 food images that ranged from ranged from fruits and vegetables, such as strawberries, apples and carrots, to high-calorie burgers, pizza and doughnuts. As an incentive, they were given the food they most craved after the fMRI scan.

High-calorie junk foods like pizza, doughnuts and burgers were the more popular choices following a sleepless night.

Walker said the findings indicate that "getting enough sleep is one factor that can help promote weight control by priming the brain mechanisms governing appropriate food choices."