Pop quiz: It’s 4 am, and you are working on an assignment that’s due at sunrise. You reach for your favorite late-night snack. Did you just grab a handful of baby carrots or potato chips? If you opted for the Ruffles, then you are not alone: during and after periods of sleep deprivation, most of us choose a higher calorie alternative to the foods that we usually eat.
Earlier theories for the link between sleep deprivation and weight gain have focused on the increased metabolic needs of a body that is active instead of sleeping. We use more energy when we are awake, and researchers thought that we ramped up our caloric intake solely to replenish this energy drain. However, this explanation doesn’t necessarily explain why our choices deteriorate from a nutritional point of view. Instead of making ourselves another peanut butter and jelly sandwich, we unhesitatingly reach for a greasy hamburger or slice of cake more often than not. Two recent studies have peered into the brain for a better answer.
In the first study, from Columbia University, participants were allowed a regimen of either nine hours or five hours of sleep a night for five nights. After this period, researchers showed them pictures of healthy and unhealthy food while looking at their brain activity through functional magnetic resonance imaging (fMRI). An fMRI allows scientists to see which parts of the brains “light up” when exposed to various stimuli. Particular areas of the brain associated with reward became more excited than normal when the sleep-deprived participants were shown unhealthy, indulgent foods, suggesting that lack of sleep makes our favorite junk food even more delicious.
In a second study, at UC Berkeley, a similar set up was arranged. The researchers gave participants one healthy night of sleep and one night of zero sleep, separated from each other by one week. After each night, participants were hooked up to an fMRI and asked to rate how strongly they wanted over eighty different foods, each accompanied by an image. Relative to the well-rested group, the fatigued group rated foods like cake and chips more highly. Distinct from the Columbia team, however, the California researchers found that these choices accompanied a marked decrease in activity in brain areas responsible for reasoning, judgment and decision-making.
These results suggest a two-pronged attack on the brain and, consequently our waistline, when we burn the candle at both ends. Not only do our favorite junk foods look more delicious, but we also lose our ability to control our ravenous impulses. So what does this mean for you as our favorite season begins to wind down? If you find yourself working hitting the gym again and again to no avail, perhaps consider taking a look at your sleep schedule. A healthy dose of z’s may just be the diet you need.