Do late nights lead you to yen for junk food the next day? That might come as no surprise, as previous research has linked less sleep with weight gain and increased cravings for fatty, salty, and sweet foods. Now, researchers may have figured out one reason for this—finding that a lack of sleep alters the rhythm of the endocannabinoid system, a neurotransmitter and receptor system that helps regulate things like mood and appetite. The study was reported on by Medical Daily, and was published in the journal SLEEP. It included 14 healthy people, ages 18 to 36, who slept a normal amount (around eight hours every night), and who participated in two four-day trials at a sleep center. During the first trial, the participants were allowed to sleep 8.5 hours each night. During the second trial, which took place four weeks later, the participants were kept up late, woken up early, and slept only 4.5 hours each night. During both trials, the participants were offered the same meals three times a day, and researchers took blood samples following each meal to measure their levels of endocannabinoids. At the end of the study, researchers noticed that:
During both sleep trials, the participants awoke with low levels of a specific endocannabinoid, 2-arachidonoylglycerol (2-AG), which then peaked around midday.
During the 4.5 hour sleep trial, midday peaks in 2-AG levels were 33% higher compared with the 8.5 hour sleep trial.
After midday, 2-AG levels in the two sleep trials diverged further: In the 8.5 hour sleep trial, 2-AG levels dropped throughout the rest of the day; but in the 4.5 hour sleep trial, 2-AG levels stayed elevated until about 9 pm.
Participants ate more calories and craved salty, sweet, and fatty foods more strongly in the afternoons and evenings during the 4.5 hour sleep trial than during the 8.5 hour sleep trial. These strong cravings and high calorie intakes were correlated with the afternoon and evening elevations in 2-AG levels.
This research confirms other evidence which has found that being sleep deprived can increase the risks of being overweight and obese. These findings could be the seed for further research on possible environmental, behavioral, or pharmacological interventions to help improve appetite regulation and prevent overeating by working with the endocannabinoid system. While that may still be a dream for the future, curbing your appetite right now might be as simple as getting to bed on time.