This Is Why You Can’t Resist French Fries When You’re Tired

There’s science behind your sleepy snack attacks.

Here’s a scene we can all relate to: After a lousy night’s sleep, you step out of the office midday to grab lunch. You fully intend to order a salad, but the scent of burgers and fries is in the air so you order that instead. This chain of events might have something to do with how a lack of sleep puts our sense of smell into overdrive — but only when food odors are wafting about, as Science of Us reports.

Image courtesy of Unsplash

New research presented at the annual meeting of the Cognitive Neuroscience Society suggests that when we’re sleep-deprived, our brains respond more strongly to food-related odors. Scientists ran an experiment where sleep-deprived adults inhaled both food and nonfood smells (like potato chips or fir trees) while getting MRI scans of their brains. The experiment was repeated a few weeks later after participants had a full night’s rest. Researchers found that the tired participants “showed greater brain activity in two areas involved in olfaction…in response to food smells than they did when well rested,” something that wasn’t evident for non-food odors, Science News writes. The takeaway: A heightened sense of smell might make it harder to walk away from delicious smelling treats.

This new finding adds to existing research suggesting our sleepy snacking has a scientific explanation, as Science of Us explains. A 2013 study found that sleep-deprived people were worse at resisting cravings for high-calorie foods than well-rested people and a study from last year found that the brains of tired study subjects contained a chemical similar to the one in cannabis known for making people munch.

This adds to a whole host of other reasons why you should aim for 7 to 9 hours of sleep a night: Your waistline — and brain — will thank you.

Read more on Science of Us.