WELLNESS
05/03/2016 07:34 am ET

What's That Eye Gunk You Wake Up With? 'Sleep Crust,' Explained.

It's completely normal.
David Zach via Getty Images

Yes, we’re talking about the (usually) white-ish gunk you find in the corners of your eyes when you wake up in the morning. Dr. Jeff Pettey, an ophthalmologist at the Moran Eye Center in Salt Lake City, Utah, and spokesman for the American Academy of Ophthalmology, gave us a rundown on what exactly that gunk is and why it’s part of a good night’s sleep.

The Huffington Post: First of all, sleep? Eye boogers? Is there actually a name for it?

Jeff Pettey: "There are a number of names for it: sleep, sleep crust, mattering, and of course, ‘eye boogers.’ The medical term is ‘rheum,’ but that term is rarely used."

What are they? Why do we get them?

"Sleep crust is made up of 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, the materials are washed away by blinking and tear production -- keeping it from gathering in the corners of the eye. Gravity makes the crust collect in the corners of the eye during sleep."

Sleep crust is a natural part of healthy eye function. Jeff Pettey, ophthalmologist and American Academy of Ophthalmology spokesman

What are they? Why do we get them?

“Sleep crust is made up of 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, the materials are washed away by blinking and tear production -- keeping it from gathering in the corners of the eye. Gravity makes the crust collect in the corners of the eye during sleep.”

Does everyone get them?

“A health functioning eye will produce the mucus, salts and oils that cause sleep crust to form, though it can occur in different amounts in different people. Some people may have so little material they may not even notice it is there. And during allergy season or when a person’s eyes are dry, more crust may develop. It should be a white or light cream color -- which is normal.

“If the discharge becomes yellow or green, that can be a sign of bacterial conjunctivitis (a common form of pink eye). If that happens, you should see an ophthalmologist.”

Are there other signs our eye boogers aren’t healthy? Or is there anything else we should know about them?

“There are chronic conditions like blepharitis (a type of inflammation), dry eye and allergic conjunctivitis that can also cause sleep crust. They could cause light crusting, but in some cases they can be so much that your eye lashes stick together. In that case I would recommend seeing an ophthalmologist. Besides the crusting, your eye doctor can help you alleviate other symptoms you may have, including redness, itchiness, watery eyes or a burning sensation in the eye.”

Sarah DiGiulio is The Huffington Post’s sleep reporter. You can contact her at sarah.digiulio@huffingtonpost.com.

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