fMRI Connects Lack of Sleep, Desire for Junk Food

Functional MRI scans show sleep-deprived people have a stronger desire for junk food, researchers found.

In a study presented this week at the annual meeting of the Associated Professional Sleep Societies in Boston, 25 healthy men and women of normal weights underwent fMRI scans while they looked at images of health and unhealthy foods. The scans were taken after the subjects’ sleep was restricted to four hours or after they were allowed to sleep for up to nine hours.

The researchers found that brain regions that were not stimulated when the subjects were viewing healthy foods were activated when presented with unhealthy foods.

“The unhealthy food response was neuronal pattern specific to restricted sleep,” said Marie-Pierre St. Onge, PhD, the principal investigator. “This may suggest greater propensity to succumb to unhealthy foods when one is sleep restricted.”

In a separate study, researchers from the University of California, Berkeley, reported on the relationship between sleep loss and obesity. In this study, 23 healthy adults underwent two fMRIs, one after a normal night’s sleep and one after a night of sleep deprivation. The subjects also rated how much they wanted various foods they saw while in the scanner.

Findings showed that when the subjects were sleep deprived, there was significant impairment in brain activity in the frontal lobe, the region critical for controlling behavior, as well as making complex choices such as food selection.

According to lead author Stephanie Greer, a graduate student at the Sleep and Neuroimaging Laboratory at the university, this failure of the frontal lobe to optimally gather information necessary to decide on which foods are best to eat, may represent a brain mechanism explaining the link between lack of sleep and obesity.

“We did not find significant differences following sleep deprivation in brain areas traditionally associated with basic reward activity, Greer said. “Instead, it seems to be about the regions higher up in the brain, specifically within the frontal lobe, failing to integrate all the different signals that help us normally make wise choices about what we eat."