It's a known fact that sleep can have a major impact on everything from your weight and mood to your ability to function like a normal human being. Now, a new study published in the journal Royal Society Open Science suggests that lack of sleep can, in fact, have an effect on your appearance—beyond the obvious dark undereye circles.
For the study, researchers from The Karolinska Institute recruited 25 students (male and female) to participate in a sleep experiment. Each person was given a kit to check how much they slept through the night and was instructed to monitor two good nights of sleep (sleeping 7-9 hours) and two bad nights of sleep (sleeping no longer than 4 hours max).
After each recorded night, researchers took pictures of the students and showed them to another group of people who were asked to analyze the photos and rate each student based on attractiveness, health, sleepiness, and trustworthiness. As expected, people who were sleep-deprived ranked lower on all counts. The group also said they'd be less likely to socialize with the students who got less sleep. (Related: The Unhealthy Food Cravings Caused By Just One Less Hour Of Sleep.)
"Findings show that acute sleep deprivation and looking tired are related to decreased attractiveness and health, as perceived by others," the study authors conclude. And the fact that one might want to avoid contact with a "sleep-deprived, or sleepy-looking individuals" is a strategy that makes sense, evolutionary speaking, the researchers explain, since "an unhealthy-looking face, whether due to sleep deprivation or otherwise" signals a health risk.
As Gayle Brewer, Ph.D., a psychology expert not associated with the study explained it to BBC, "Judgment of attractiveness is often unconscious, but we all do it, and we are able to pick up on even small cues like whether someone looks tired or unhealthy."
Of course, "most people can cope just fine if they miss out on a bit of sleep now and again," lead researcher Tina Sundelin, Ph.D., told BBC. "I don't want to worry people or make them lose sleep over these findings." (See what she did there?)
The study sample size was small and there's still a lot more research to be done when it comes to determining how important those 7-8 hours of sleep really are, but we can always get behind another reason to catch up on some much-needed zzz's. So for now, try your best to avoid those lost hours of mind-numbing Instagram scrolling before bed—and get some damn beauty sleep.