Washington, June 11 (ANI): The sight of unhealthy food during a period of sleep restriction activates reward centres in the brain that are less active when an individual gets adequate sleep, a new study has revealed.

In the new study, which used brain scans to better understand the link between sleep restriction and obesity, researchers from Roosevelt Hospital Center and Columbia University in New York performed functional magnetic resonance imaging (fMRI) on 25 men and women of normal weights while they looked at images of healthy and unhealthy foods.

The scans were taken after five nights in which sleep was either restricted to four hours or allowed to continue up to nine hours, and the results were then compared.

The same brain regions activated when unhealthy foods were presented were not involved when we presented healthy foods, Marie-Pierre St-Onge, principal investigator of the study, said.

The unhealthy food response was a neuronal pattern specific to restricted sleep. This may suggest greater propensity to succumb to unhealthy foods when one is sleep restricted, St-Onge said.

Previous research has shown that restricted sleep leads to increased food consumption in healthy people, and that a self-reported desire for sweet and salty food increases after a period of sleep deprivation.

According to St-Onge, the new study's results provide additional support for a role of short sleep in appetite-modulation and obesity.

The results suggest that, under restricted sleep, individuals will find unhealthy foods highly salient and rewarding, which may lead to greater consumption of those foods.

Indeed, food intake data from this same study showed that participants ate more overall and consumed more fat after a period of sleep restriction compared to regular sleep. The brain imaging data provided the neurocognitive basis for those results, St-Onge added.

The findings of the study will be presented at SLEEP 2012, the 26th annual meeting of the Associated Professional Sleep Societies (APSS) in Boston. (ANI)