Junk food Boston - Agencies The sight of junk food in sleep-deprived people activates reward centres in their brains, but not in those who are well-rested, US researchers say. Marie-Pierre St-Onge, the study\'s principal investigator, and colleagues at St Luke\'s-Roosevelt Hospital Centre and Columbia University in New York, performed functional magnetic resonance imaging on 25 men and women of normal weight while they looked at pictures of healthy and unhealthy foods. The scans were taken after five nights in which sleep was either restricted to 4 hours or allowed to continue up to 9 hours. \"The same brain regions activated when unhealthy foods were presented were not involved when we presented healthy foods,\" St-Onge said in a statement. \"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.\" Previous research showed restricted sleep was linked to increased food consumption in healthy people, and many desire sweet and salty food increases after a period of sleep deprivation. \"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,\" St-Onge said. The finding was presented at Sleep, the 26th annual meeting of the Associated Professional Sleep Societies in Boston.