Researchers from St. Luke's - Roosevelt Hospital Center and Columbia University in New York were conducting the study to examine the link between sleep restriction and obesity.
According to a press release
, the researchers found people tended to gravitate towards junk food after experiencing sleep restriction, as opposed to when a person has had a good night's rest.
The study involved 25 men and women of normal weights. Researchers performed functional magnetic resonance imaging (fMRI) on these participants as they looked at photos of healthy and unhealthy foods. The participants in this study were either restricted to four hours of sleep or allowed nine hours for five nights.
"The same brain regions activated when unhealthy foods were presented were not involved when we presented healthy foods," said Marie-Pierre St-Onge, PhD, the study's principal investigator. "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."
It has previously
been suggested people eat more foods high in fat and protein when they are tired. A 2011 study conducted by the Columbia University's New York Obesity Research Center, with St-Onge leading this study
as well, found women who slept only four hours per night consumed, on average, 329 more calories a day. For men there was an increase, although not as much; on average men consumed 263 additional calories a day when they were tired.
This new study involving the brain's reaction to foods helps support the earlier theory there is a direct role between the amount of sleep an individual gets and a tendency towards weight gain. It is believed individuals look for the quick burst of energy/high calorie foods when they are tired. Researchers found the sleep deprived subjects tended to react to foods such as pepperoni pizza, cheeseburgers and cake.
"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. "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."
and U.S. News
reported on another, separate study recently conducted which suggests higher level brain functions contribute to a person's tendency to reach for the junk food when they are tired. This study suggested people are too fatigued to make good decisions and weigh out the pros and cons when making food choices.
Both studies were presented at the Associated Professional Sleep Societies in Boston yesterday, but have not yet been peer reviewed; data and conclusions should be viewed as preliminary at this time.