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Sleep is a vital part of one's day. Not only does sleeping rejuvenate the body, it also promotes cognitive abilities. Several studies have found evidence that a lack of sleep leads to a poorer attention span, which then affects academic and work performances. Now, according to a new study, sleep deprivation could lead to an increase craving for junk food. This craving, when fulfilled, would then lead to obesity.

For this study, the researchers headed by Matthew P. Walker, professor of psychology and neuroscience at the University of California, Berkeley, recruited a small sample size of 23 healthy men and women. Each individual was assigned to two different routines that were followed one after the other with a one-week separation. For one situation, the participants were asked to come into the lab where they slept for around eight hours, which is considered to be a normal night of rest. When they woke up, the researchers offered them toast and strawberry jam. The participants then looked through 80 pictures of different types of food and rated them according to how badly they wanted to eat them. During this process, brain activity was measured. For the second regimen, the participants followed the exact same routine but they did so without any sleep at all. Since they had to stay awake for eight hours, they were given snacks to accommodate for any loss in energy.

The researchers discovered that when the participants were deprived of sleep, they were more likely to crave foods that were high in calories, such as desserts, chocolate and potato chips than when they slept a good eight hours. These types of food were around 600 calories more than the food that they wanted after a full night's rest. Not only were the sleep deprived participants asking for higher-calorie foods, their brain scans revealed that their amygdala, which is responsible for regulating emotions such as desire for food, experienced increased activity. The researchers also noted that activity in the cortical areas of the frontal lobe, which is responsible for decision-making, was reduced.

"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," Walker said according to HealthDay. "High-calorie foods also became 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."

Although the researchers could not pinpoint exactly why brain activity shifts due to sleep deprivation, they are confident that the association they found is strong. This finding suggests that people who want to avoid packing on the pounds should consider fixing their sleeping schedules.

"There's something that changes in our brain when we're sleepy that's irrespective of how much energy we need," commented Dr. Kenneth P. Wright, who was not a part of the study according to the New York Times. Wright is the director of the sleep and chronobiology lab at the University of Colorado at Boulder. "The brain wants more even when the energy need has been fulfilled." 

The study was published in Nature Communications.