The sight of unhealthy food after inadequate sleep activated reward centers in the brain that were less active when participants experienced normal sleep, according to a new study aimed at understanding the link between sleep restriction and obesity.
The researchers performed MRI scans 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. The results were then compared and the findings presented at the SLEEP 2012 conference.
"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," said researcher Marie-Pierre St-Onge, from Columbia University. "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 study shows that sleep deprivation significantly impaired brain activity in the frontal lobe, a region critical for controlling behavior and making complex choices, such as the selection of food to eat. That suggests that sleep loss may prevent the higher brain functions normally critical for making appropriate food choices, rather than necessarily changing activity in deeper brain structures that react to basic desire.
"The same brain regions activated when unhealthy foods were presented were not involved when we presented healthy foods," said St-Onge. "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."
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Source: American Academy of Sleep Medicine