Sunday, June 10, 2012

Sleep deprivation makes you want unhealthy food

Despite the fact that we have not quite figured out yet why it is that complex organisms need sleep in order to function properly, we do know it has to be very important. We all know that awful feeling of being sleep-deprived, even though it is still unknown what consequences it has on the long term. Previous research has revealed that a lack of sleep increases food craving, because it activates brain areas involved with appetite. Now, a different study shows that it also increases desire for eating junk food. Altogether, these studies show that sleep deprivation is not only unhealthy by itself, it also leads to unhealthy behaviour.

To assess the effect of sleep deprivation on the brain, scientists performed an MRI scan on the brains of volunteers that took part in the study. A total of 25 men and women were enrolled in the study, which were subjected to a series of sleep-restricted nights of only four hours. As comparison, brain scans were taken during a period where the participants were allowed to sleep for up to nine hours.

After evaluating the scan results, researchers found that sleep deprivation caused activation of reward centres in the brain when the participants were given unhealthy foods. That, of course, stimulates the consumption of junk food, as humans always seek for adequate stimulation of these brain areas. When presented with healthy foods, the reward centres remained dormant. Curiously, brain scans from the comparison setup did not show any activation of reward centres when presented with junk food.

Satisfying the reward centres, which involves release of specific communication molecules in the brain, is very important for us human beings. Not being able to get a sense of reward or satisfaction can lead to unhappiness or even depression. Being sleep-deprived leads to an increase in desire for junk food, which of course is not very beneficial. Because sleep deprivation was already known to increase food cravings, this study provides more evidence for the hypothesis that not getting enough sleep is an important factor for obesity.

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