Snacking more likely if you are tired12th June 2012
Studies of eating behaviour in people who have not had enough sleep show that we are far more likely to make unhealthy food choices when we are tired.
Sleep-deprived people are more likely to reach for unhealthy snacks like crisps and sweets than people who are well rested, according to recent studies in New York and California.
The researchers monitored areas of the brain that are most active when people looked at healthy or unhealthy foods, and found that the reward centers of the brains of study participants who had not had enough sleep were activated by pictures of unhealthy foods.
According to Marie-Pierre St-Onge of Columbia University's Institute of Human Nutrition in New York, the team found that the regions of the brain involved with addiction and pleasure-seeking behaviours were more strongly activated when subjects had only had a small amount of sleep.
St-Onge and fellow researchers will present their findings at the annual meeting of the Associated Professional Sleep Societies in Boston.
While a smaller study carried out by researchers at the University of California in Berkeley did not find such a marked difference between those who were tired and those who were not, they did find that frontal lobe activity in sleep-deprived subjects was significantly impaired.
The frontal lobes help control behaviour and make complex choices, which suggested that sleep-deprived people would find it hard to make healthy food choices because of diminished choice-making abilities.
The California researchers studied functional magnetic resonance images (fMRI) from 16 healthy young adults who were asked to rate their desire for 80 different foods during tests. They were tested once after a full night's sleep and again after 24 hours of sleep deprivation.
St-Onge's study involved fMRI scans of 25 normal-weight men and women who had undergone five nights with only four hours of sleep and five nights of nine hours' sleep.
The participants were shown pictures of fruits, vegetables and oatmeal as well as pepperoni pizza and sweets, as well as of non-food items like office supplies.
The unhealthy foods "lit up" the brain's reward centres only in people whose sleep was restricted. The same people had no such activation in the brain's reward centre when they saw the unhealthy foods once they had been allowed to rest a full night.
St-Onge said the difference was unlikely to be the result of cognitive control, and that people who were deprived of sleep were likely to eat unhealthy foods even if they knew it was not a healthy food choice.
According to dietician Samantha Heller, the body looks for calorie-dense foods that give it quick energy when it is tired.
Heller said that in today's society, people often turn to processed carbohydrates rather than a piece of fruit for a quick energy boost. But the temporary energy boost from processed foods does not last, and the best remedy for sleep deprivation is sleep.
She advised people to keep healthier snacks readily available in their homes and in the workplace, making it easier to go for the healthier option.
St-Onge said a good night's sleep of between seven and eight hours was especially important if people were trying to lose weight.
However, the data and conclusions in the study should be viewed as preliminary until published in a peer-reviewed journal.
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Title: Snacking more likely if you are tired
Author: Luisetta Mudie
Article Id: 22101
Date Added: 12th Jun 2012