Natural Health News — A sleepless night makes us more likely to reach for doughnuts or pizza than for whole grains and leafy green vegetables, suggests a new study that examines the brain regions that control food choices.
The findings, which build on existing research in this field, shed new light on the link between poor sleep and obesity.
Using functional magnetic resonance imaging (fMRI), University of California at Berkeley researchers scanned the brains of 23 healthy young adults, first after a normal night’s sleep and next, after a sleepless night.
During the MRI participants viewed a series of 80 food images that ranged from high-to low-calorie and healthy and unhealthy, and rated their desire for each of the items. As an incentive, they were given the food they most craved after the scan.
Food choices presented in the experiment ranged from fruits and vegetables, such as strawberries, apples and carrots, to high-calorie burgers, pizza and doughnuts. The latter are examples of the more popular choices following a sleepless night.
What they saw was that sleep deprived brains showed impaired activity in the frontal lobe – which governs complex decision-making – but increased activity in deeper brain centres that respond to rewards.
In addition, the study, published in the journal Nature Communications, found that people favoured unhealthy snack and junk foods when they were sleep deprived.
“What we have discovered is that high-level brain regions required for complex judgements and decisions become blunted by a lack of sleep, while more primal brain structures that control motivation and desire are amplified,” said lead author Matthew Walker, a UC Berkeley professor of psychology and neuroscience.
Walker added, “high-calorie foods also became significantly more desirable when participants were sleep-deprived. This combination of altered brain activity and decision-making may help explain why people who sleep less also tend to be overweight or obese.”
A piece of the puzzle
Previous studies have linked poor sleep to greater appetites, particularly for sweet and salty foods, but according to the researchers their findings provide a specific brain mechanism explaining why food choices change for the worse following a sleepless night.
Increasingly science is showing that there is more to rising levels of obesity than simply the number of calories we consume. Sleep deprivation in a culture that prides itself on being 24/7 is one aspect. Chemical exposure is another. For more on weight gain not specifically related to calories in/calories out see our article Programmed to be Fat?
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