It’s the best beauty treatment out there—and doesn’t cost a dime.

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When you were younger, how many times did you ignore your mama when she subtly encouraged you to go to bed early, hinting that you ought to “get your beauty sleep”? It’s one of those common phrases we Southerners love to toss around, like “fit to be tied” and “preaching to the choir.” But it turns out, we should have been listening to Mama, because there’s some serious truth behind the statement. Mattress brand Sealy recently conducted a study in the United Kingdom that aimed to determine whether there was a link between quantity and/or quality of sleep and an improved physical appearance.

Their study did find a strong correlation, with 60 percent of the participants reporting that “they believe the quality of sleep they get has a positive effect on their physical appearance.” Plus, they found that people who got an average of 9 hours and 10 minutes of sleep a night (citing a 9:45 pm bedtime and rising at 6:55 am as optimal hours to hit the hay) were “most likely to report positive benefits to their physical appearance.” Now, not all of us have the luxury of getting 7 hours of sleep every night, let alone 9. But it’s worth trying to sleep a little longer every chance you get. As the study points out, sleep is one of the best ways to maintain and bolster your well-being and physical appearance—and it’s absolutely free.

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There’s additional science to back this up as well. We know that the body restores itself while we sleep—one of the biggest benefactors of increased sleep is your skin. Your body produces collagen while you’re sleeping, staving off wrinkles and sagging skin. During a full sleep cycle, the body also releases toxins from the skin, rehydrates itself, and increases blood flow, which means less puffy skin and fewer dark circles under your eyes. And as if that wasn’t enough incentive, higher stress levels can cause the onset of hair loss. The best way to naturally reduce stress and its accompanying damaging hormones? You guessed it: a good night’s rest. So the next time you feel your bed calling before anyone else has called it a night, go ahead and give in—and confidently tell folks, “I’m going to get my beauty sleep.”