Lack of Sleep Could Be Why You Have the Munchies

We all know the benefits of a good night's sleep. Better skin, increased concentration levels, the ability to make civilised conversation without first ingesting large quantities of caffeine. However wild your weekend plans, there's a pretty strong case for being tucked up in bed with a camomile tea and comfortingly dull book by 10.30 PM.

Even more so following the results of a new study from the University of Chicago. According to researchers, that insatiable craving for toffee popcorn-flavoured macarons (they're a thing, right?) could be linked to how late you stayed up watching cat Vines last night.

The university's research found that lack of sleep may alter brain chemicals in a similar way to the hunger-boosting ingredient found in cannabis. Basically, a bad night's sleep could result in a bad case of the munchies come tomorrow morning.

Published in the journal Sleep, researchers asked 14 men and women in their twenties to spend two four-day sessions in a clinical research centre. On one visit, the participants had an average of seven and a half hours sleep, but only four hours and 11 minutes on the other visit. During each stay, participants ate identical meals at 9 AM, 2 PM, and 7 PM.

After the fourth night on each of their stays came the good bit: snacks. Participants were offered a range of treats, including less healthy options such as biscuits and crisps. Researchers found that the sleep-deprived participants felt a strong urge to binge on these high-fat snacks, despite consuming a meal containing 90 percent of their recommended daily calorie intake just two hours earlier.

These sleepy snackers typically ate 300 calories, which was far more than required to make up for the extra hours they had spent awake.

The researchers put this down to endocannabinoid 2-AG, a chemical that increases the pleasure experienced when eating food, especially during binges on high-fat snacks. They found that the brains of sleep-deprived participants had higher levels of endocannabinoids.

Erin Hanlon, who lead the study, explained: "We know that marijuana activates the endocannabinoid system and causes people to overeat when they are not hungry, and they normally eat yummy sweet and fatty foods. Sleep restriction may cause overeating by acting in the same manner."

Researchers also found that the cravings of sleep-deprived participants were most intense in the late afternoon or evening. This could be down to levels of 2-AG in their brains rising by 33 percent after midday, before peaking at 2 PM and remaining high until 9 PM—prime time for that afternoon biscuit tin dive or post-dinner chocolate bar.

Hanlon added: "If you have a Snickers bar and you've had enough sleep, you can control your natural response. But if you're sleep deprived, your hedonic drive for certain foods gets stronger and your ability to resist them may be impaired."

The study isn't the first to link sleep loss with higher risk of obesity—tired people are often less motivated to seek out healthy foods or take exercise, after all—but Frank Scheer of Brigham and Women's Hospital in Boston said that its findings reveal new insight into how "sleep restriction leads not only to increased calorie intake" but also "changes in the hedonic aspects of food consumption."

He's not wrong. Is there anything more blissfully hedonic than semi-consciously devouring pizza slices in bed?