Sleep in your eyes, sleep crust, or eye gunk—whatever you call it. We all get that crusty stuff in the corners of your eyes when you wake up in the morning. There's actually a medical term for it. It's called rheum, though you rarely hear it used, and it's all part of a good night's sleep.
Jeff Pettey, MD, an ophthalmologist at John A. Moran Eye Center, answers questions about the phonemenom.
What Exactly is Rheum and Where Does it Come From?
Sleep crust is a mix of mucus, exfoliated skin cells, oils, and tears produced or shed by the eye during sleep. It's a natural part of healthy eye function.
"During the day, all of that stuff is washed away by blinking natural tears, which keep it from sticking around," Pettey says. "But when you're asleep, gravity and the fact that you're not blinking, makes it collect in the corners of the eyes."
Does Everyone Have Rheum?
Pretty much everyone wakes up with sleep crust. A healthy, functioning eye will produce the mucus, salts, and oils that cause it to form, though it can show up in different amounts in different people.
"Some people may have so little material that they may not even notice it's there," Pettey says. "But during allergy season, or when your eyes are dry, you may get a little more. It should be white or light cream color—which is normal."
What If You Have a Lot of it or it's a Different Color?
If the discharge is yellow or green, that can be a sign of bacterial conjunctivitis—a common form of pink eye. In that case, you should see an ophthalmologist.
There are also chronic conditions like blepharitis (a type of inflammation), dry eye, and allergic conjunctivitis that can also cause sleep crust. In some cases it could be enough to make your eyes stick together. In those cases, see an ophthalmologist.
What's the best way to remove rheum?
Although it's tempting to rub your eyes with your hands in the morning, try to resist. It's never a good idea, as germs on your hands could lead to an eye infection.
The best way to clean your eyes is to lay a washcloth soaked with very warm water on your eyelids and lashes and gently clean them. If your eyes seem to be extra-sticky, relax and leave the washcloth on there for a few minutes.