How Lack of Sleep Affects Junk Food Cravings

We all know the importance of getting a good night’s sleep regularly, but according to the CDC, 1/3 of adults don’t get enough sleep. At least seven hours per night is recommended, as chronic sleep deprivation is associated with an increased risk of developing unhealthy conditions like obesity, diabetes, high blood pressure, heart disease and stroke. But it’s not just the body that suffers — too little sleep can also cause mental distress, junk food cravings and poor decision-making. Consider that some of those decisions involve what you eat and drink, and the bodily effects of sleep quality and duration are compounded.

A 2012 Swedish study published in The Journal of Clinical Endocrinology & Metabolism looked at the connection between sleep and junk food cravings. They noted sleep deprivation is known to stimulate appetite and food intake, so they hypothesized tired humans are more sensitive to the “rewarding food stimuli” of high-calorie foods. After the study period, they found participants who experienced acute sleep loss (those who were not allowed to sleep as much as the others) reported increased hunger and displayed changes in their brains that showed increased activation in response to food images.

The longer the sleep deprivation lasts, the worse things get. The study results suggested prolonged periods of inadequate sleep lead to a greater reward response in anticipation of food. These changes can drive hedonic impulses to consume unhealthier food and to eat larger quantities than necessary.

The researchers note their findings may highlight a potentially important mechanism that is contributing to the growing levels of obesity in Western society. In other words: We don’t sleep enough, and that may be one reason why we’re collectively gaining weight.

A 2019 Northwestern University study published in the journal eLife looked specifically at why we crave junk food after a night of bad sleep. Like the Swedish study, it noted sleep deprivation impacts food intake and is associated with a preference toward high-calorie options. But it also found our noses are to blame.

According to the researchers, when we’re tired, the olfactory system goes into overdrive to identify food. It also changes how it communicates with the brain, which results in our nose steering our decision-making toward more energy-dense options. This may be why we feel more susceptible to enticing aromas when we’re tired. Just picture the commercials and cartoons showing people rising from bed, as if on a string, as their noses follow the wafting scents of olfactory delights, like bacon and coffee.

In the study, the scientists noted that individuals who slept less were more likely to snack throughout the day, choosing not only more food but higher-calorie foods.

“We found participants changed their food choices,” said the study’s senior author, Thorsten Kahnt, an assistant professor of neurology at Northwestern’s Feinberg School of Medicine. “After being sleep deprived, they ate food with higher energy density (more calories per gram) like doughnuts, chocolate chip cookies and potato chips.”

So, if you want to curb those junk food cravings, start with a good night’s sleep. Not only will you make better food choices the next day, but keep it up, and you’ll feel less susceptible to the charms of sugary, high-fat foods overall. This can help you stave off weight gain, as well as associated conditions like diabetes, high blood pressure and heart disease.

Originally published December 2020, updated May 2022

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