After performing a study, UC Berkeley researchers discovered that sleep deprivation makes high-calories foods significantly more desirable.

Using functional magnetic resonance imaging (fMRI), the researchers scanned the brains of 23 healthy young adults, first after a normal night’s sleep and then after a sleepless night. They found impaired activity in the sleep-deprived brain’s frontal lobe, which governs complex decision-making, but increased activity in deeper brain centers that respond to rewards. Moreover, the participants favored unhealthy snack and junk foods when they were sleep deprived.

Matthew Walker, a UC Berkeley professor of psychology and neuroscience and senior author of the study stated that the high-level brain regions required for complex judgments and decisions became blunted by lack of sleep, while more primal brain structures that control motivation and desire became amplified. This may be one of the many causes of why people who sleep less also tend to be more overweight or even obese.

In this study, scientists measured brain activity as members saw an arrangement of 80 food pictures that ran from high-to low-calorie and healthy and unhealthy, and rated their craving for each of the food pictures. As a incentive, they were given the food they most wanted after the MRI check.  The food pictures shown in the experiment ranged from fruits and vegetables, like strawberries, apples, and carrots, to high calorie burgers, pizza, and doughnuts. The high calorie choices were the most popular after a sleepless night.

Older studies have shown that poor sleep is linked to greater appetites, particularly for sweet and salty foods, but the most recent studies shows evidence of why the food choices change after a restless sleep. “The results shed a new 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.

“Getting enough sleep is one factor that can help promote weight control by priming the brain mechanisms governing appropriate food choices.” said Walker according to the new findings by the sleep deprivation study.