Sleep Deprivation and Weight Gain
Hormones control a variety of bodily functions including metabolism and appetite. Normally, the hormone leptin tells your brain when you’re full, so you stop eating. During sleep, leptin levels rise letting your brain know your body has enough energy to make it through the night. Inadequate sleep, even for one night, results in a decrease in leptin levels, triggering your brain to seek more energy in the form of food.
At the same time, sleep deprivation increases the levels of ghrelin, another hormone that sends the opposite signal to the brain. Higher levels of ghrelin make you feel the urge to eat even if you’re not very hungry. The end result of insufficient sleep is a double whammy of altered hormone levels that tell your brain—in two ways—to eat and keep eating.
The Science Behind Unhealthy Food Cravings
The news about sleep deprivation and weight gain gets worse from there. What you crave to eat when you are sleepy is just as destructive to your healthy diet as the amount you want to eat. Eric Hanlon, a behavioral neuroscientist at the University of Chicago, led a study to explain why people crave sugary and fatty foods when they are sleepy. His findings, published in the journal Sleep, reveal that the endocannabinoid system may influence our fatigue-fueled craving for foods that are high in carbs, sugar, and fats. The endocannabinoid system, made up of endocannabinoids, receptors, and enzymes, plays a role in regulating a range of functions like sleep and mood, but also appetite.
Hanlon compared levels of one of the most abundant endocannabinoids, 2-AG, in people who slept 8 hours to those in people who only got 4.5 hours. He found the mid-day levels of 2-AG in people whose sleep was restricted were significantly higher than in people who slept 8 hours. The sleep-deprived participants also reported increases in hunger and appetite while their 2-AG levels were elevated and found their cravings for high calorie, high carb snacks irresistible.
Hanlon’s findings suggest sleep deprivation activates the endocannabinoid system to produce more 2-AG, which results in the urge to eat more and an inability to resist indulging in fatty, sugary foods.
Hanlon believes the urge to indulge in energy-dense foods is also influenced by the reward center of the brain. You don’t have to be an endocrinologist to know that your brain’s reward center is activated when you eat a sumptuous and tasty meal. When people are well-rested and have normal levels of 2-AG, they can easily (well, relatively easily) resist eating too much rich food no matter how psychologically rewarding such foods may feel. He believes the reason why people with elevated levels of 2-AG crave rich foods has to do with the quest for the psychological reward that comes with indulging in a rich snack.
But what is the exact mechanism for that quest? Hanlon says, “We don’t know.”
However, his study contributes one more piece to the complicated puzzle illustrating the relationship between sleep deprivation and weight gain.