What Really Happens When You Sleep In Your Makeup, Anyway? Derms Weigh In 

Always remove your makeup before bed. If beauty came with a manifesto, many would consider it declaration No. 1. It's certainly the first piece of advice I received as a teen about to (way too generously) apply her first flick of gel liner, and it remains a cautionary tale for skin care through the ages. To painstakingly care for your skin, it's best to remove all traces of the day before crashing into bed, no matter how loudly it's calling your name. 

But what really happens to your skin when you go to bed with some spots of concealer? We know sleeping in makeup on the regular is a major no (and, trust, this article will not encourage you to hop into bed with a full face), but you may slip up from time to time (we're only human!). What happens if you succumb to just one night of exhaustion? 

First and foremost, sleeping in makeup can lead to clogged pores. Foundations and concealers don't seep into your skin but sit atop it (which is a good thing; you don't want makeup penetrating the epidermis), and this creates an environment for acne to thrive, especially during the night. "As you sleep, your skin cells turn over, and you can produce oil and actually sweat in your sleep," says board-certified dermatologist Jeanine Downie, M.D. "This makes sleeping in your makeup 10 times worse."

Put it this way: Makeup creates a film over your pores so the sebum and sweat have nowhere to go, which affects your natural oil production—a recipe for clogged pores and breakouts.

Aside from acne, sleeping in your makeup can also cause premature skin aging. Pollutants and daily grime build up on your skin as the day goes on (even if you aren't wearing any makeup at all), which can contribute to oxidative stress, dull, crepey skin, and fine lines if you don't cleanse before bed. "Pollution can subject the skin to free radicals, which can contribute to the breakdown of collagen and elastin and lead to aging of the skin, so it's important to cleanse the skin to avoid these effects," adds board-certified dermatologist Hadley King, M.D.

And eye makeup especially deserves its own moment: Your eyes are one of the most sensitive areas to contact dermatitis and irritation—so if, say, you smudge some shadow into your eyes while you sleep, the formula may irritate your delicate orbs. Says King, "Sleeping with eye makeup can be particularly dangerous, resulting in irritation, allergic reactions or more severe conditions, such as infections or a scratched cornea."  

The thing is, it takes some time—like, a nightly cadence—for the effects we mentioned above to start showing up. If you slip up after one forgetful night, you likely won't see dramatic consequences, unless, of course, you have an allergic reaction to your eye makeup. "But it can possibly contribute to clogged pores, dull complexion, increasing breakdown of collagen and elastin—and this effect will increase with repeated nights," warns King. Translation: It's not the end of the world if you drift off without a proper cleanse; just don't make it a habit.  

If you do wake up and find your lashes crunchy with dried mascara, don't panic: Thoroughly remove your makeup in the morning, Downie suggests, perhaps lightly exfoliating, too, to increase cell turnover and reveal fresh unscathed skin. Aside from moisturizer and sunscreen, you might want to keep your products light or skip makeup altogether—let your skin have a break from heavy makeup for the day.