Craving Junk Food? Perhaps You Need More Sleep
August 7, 2013

Desire For Junk Food Increases After Sleepless Nights

redOrbit Staff & Wire Reports - Your Universe Online

People are more likely to reach for junk food than healthier culinary alternatives following a sleepless night, claims research published Tuesday in the journal Nature Communications.

Investigators from the University of California-Berkeley (UC-Berkeley) used functional magnetic resonance imaging (fMRI) to scan the brains of 23 healthy young adults. Each study participant underwent the fMRI procedure twice - once after a normal night's sleep and a second time following a sleepless night - the authors reported.

They discovered impaired activity in the frontal lobe, which governs complex-decision making skills, in those who were sleep deprived. However, they reported increased activity in deeper brain areas linked to rewards, and found that participants who received an inadequate amount of rest preferred unhealthy snack and junk foods.

"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," senior author Matthew Walker, a UC Berkeley professor of psychology and neuroscience, said in a statement.

In addition, Walker noted 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."

Past research had linked poor sleep to an increased appetite, especially for foods that are sweet or salty. However, the new study found a specific mechanism in the brain explaining why people make worse food choices following a sleepless night, Walker said.

He and his colleagues measured the brain activity of the study participants as they viewed a series of 80 food images, including both healthy and unhealthy choices of various caloric values. Each person's level of desire for each food item were rated, and as a bonus, each person was given the food he or she craved most following the fMRI.

"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.

The food choices offered to the study participants included various fruits and vegetables, such as apples and carrots, as well as hamburgers, pizza, doughnuts, and other high calorie foods, the researchers said. One positive that did come out of their work, Walker added, was that their findings indicated that getting an adequate amount of sleep is a factor that could help combat obesity by "priming the brain mechanisms governing appropriate food choices."

In related research published back in May, Steven Shea of Oregon Health & Science University's Center for Research on Occupational and Environmental Toxicology and colleagues reported that a person's internal circadian rhythm could be the cause of increased appetite in the evening.

Additionally, earlier this year, a study written by Heather Leidy, an assistant professor at the University of Missouri's Department of Nutrition and Exercise Physiology, and colleagues touted the benefits of eating a protein-rich breakfast. Doing so could help men and women better control their appetites and reduce their desire to snack on sugary or fatty foods later on in the day, she explained.