As anyone who has pulled an all-nighter can attest, it’s never a good idea to try to function on a lack of sleep. Aside from making you feel drowsy all day, poor sleeping habits may also cause you to consume too many calories.

Snacking and Sleeping

This was the conclusion of a 2016 study, published in the journal Sleep. For this project, the study authors recruited a small group of 14 men and women, all of whom were in their twenties. Each volunteer was required to reside at the University of Chicago’s Clinical Research Center for two separate four day periods.

During one of these periods, the subjects were required to spend 8.5 hours in bed each night. On average, during this stay the participants slept for 7.5 hours on average. In contrast, the volunteers slept far less during their other stay in the Research Center, averaging only 4.2 hours nightly.

Meal Time

Aside from following specific sleeping schedules, the subjects were also asked to consume meals at certain times during the day. Breakfast was served at 9 a.m, lunch at 2 p.m. and dinner at 7 in the evening. Finally, the authors were also highly interested in the subject’s blood levels of the hormones ghrelin and leptin, as well as a substance called 2-arachidonoylglycerol (2-AG). This study was the first to measure levels of 2-AG following various periods of sleep.

Reading the Signs

Normally, our levels of 2-AG remain low during the nighttime hours, and proceed to slowly increase as the day progresses. In the early afternoon, 2-AG levels are usually at their highest.

A lack of sleep completely disrupted this cycle noticeably. In this state, the subjects 2-AG levels were consistently high throughout the evening. At the same time, the participants reported higher than normal food cravings, and consumed nearly double the fat content when allowed to eat snacks.

Study author Erin Hanlon summarized her team’s findings in a University of Chicago press release. “We found that sleep restriction boosts a signal that may increase the hedonic aspect of food intake, the pleasure and satisfaction gained from eating,” noted Hanlon. “Sleep restriction seems to augment the endocannabinoid system, the same system targeted by the active ingredient of marijuana, to enhance the desire for food intake.”