Getting enough sleep is one factor that can help promote weight control by priming the brain mechanisms governing appropriate food choices. The less you sleep, the more you may crave junk food and various high-calorie items. In northern California last month, a new study from the University of California, Berkeley found that sleep deprivation can make us crave junk food more than healthy food.
A sleepless night makes us more likely to reach for doughnuts or pizza than for whole grains and leafy green vegetables, suggests the study from UC Berkeley that examines the brain regions that control food choices. The findings shed new light on the link between poor sleep and obesity, says an August 6, 2013 news release by Yasmin Anwar, "Sleep deprivation linked to junk food cravings."
Using functional magnetic resonance imaging (fMRI), UC Berkeley researchers scanned the brains of 23 healthy young adults, first after a normal night’s sleep and next, after a sleepless night. They found impaired activity in the sleep-deprived brain’s frontal lobe, which governs complex decision-making, but increased activity in deeper brain centers that respond to rewards. Moreover, the participants favored unhealthy snack and junk foods when they were sleep deprived.
“What we have discovered is that high-level brain regions required for complex judgments and decisions become blunted by a lack of sleep, while more primal brain structures that control motivation and desire are amplified,” explains Matthew Walker in the news release, "Sleep deprivation linked to junk food cravings." Walker is a UC Berkeley professor of psychology and neuroscience and senior author of the study published on August 6, 2013 in the journal Nature Communications. Check out "The impact of sleep deprivation on food desire in the human brain."
Epidemiological evidence supports a link between sleep loss and obesity. However, the detrimental impact of sleep deprivation on central brain mechanisms governing appetitive food desire remains unknown, says the study's abstract. Sleep deprivation also impacts the immune system. You also may wish to check out another study's abstract, "Sick and tired: does sleep have a vital role in the immune system?"
Scientists reported that sleep deprivation significantly decreases activity in appetitive evaluation regions within the human frontal cortex and insular cortex during food desirability choices, combined with a converse amplification of activity within the amygdala. Moreover, this bi-directional change in the profile of brain activity is further associated with a significant increase in the desire for weight-gain promoting high-calorie foods following sleep deprivation, the extent of which is predicted by the subjective severity of sleep loss across participants.
These findings provide an explanatory brain mechanism by which insufficient sleep may lead to the development/maintenance of obesity through diminished activity in higher-order cortical evaluation regions, combined with excess subcortical limbic responsivity, resulting in the selection of foods most capable of triggering weight-gain. That means too much stimulation of a part of the brain that leads to not being able to fall asleep after eating high-calorie foods. See, "Lack of Sleep Leads to Unhealthy Food Choices."
High-calorie foods became more desirable when the study's participants were sleep-deprived
Matthew Walker, a UC Berkeley professor of psychology and neuroscience and senior author of the study published on August 6, 2013 in the journal Nature Communications, also explains in the news release that “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.”
Previous studies have linked poor sleep to greater appetites, particularly for sweet and salty foods, but the latest findings provide a specific brain mechanism explaining why food choices change for the worse following a sleepless night, Walker says in the news release.
“These results shed light on how the brain becomes impaired by sleep deprivation, leading to the selection of more unhealthy foods and, ultimately, higher rates of obesity,” says Stephanie Greer, in the news release. Greer is a doctoral student in Walker’s Sleep and Neuroimaging Laboratory and lead author of the paper. Another co-author of the study is Andrea Goldstein, also a doctoral student in Walker’s lab.
After the MRI scan, participants in the study were given food they most craved
In this newest study, researchers measured brain activity as 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 MRI 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.
On a positive note, Walker says in the news release the findings indicate that “getting enough sleep is one factor that can help promote weight control by priming the brain mechanisms governing appropriate food choices.” You also may wish to see the article, "Obesity Linked To Lack Of Sleep."