The crusty or gooey stuff you find in the corners of your eyes each morning is called rheum. It’s a mix of mucus, oils, skin cells, and dust that your eyes produce throughout the day and night as part of their normal cleaning process. During the day, blinking washes this material away with your tears. At night, because you’re not blinking, it collects in the corners of your eyes and along your lash line, where it dries into that familiar crust.
What Rheum Is Made Of
Your eyes are constantly producing a thin film of tears to stay moist and protected. That tear film has three layers: a watery layer, a mucus layer produced by the clear membrane covering your eye (the conjunctiva), and an oily layer made by tiny glands along the edge of your eyelids called meibomian glands. The oil from these glands, called meibum, sits on top of your tears and keeps them from evaporating too quickly.
Throughout the day, all three layers mix with debris like dust, dead skin cells, and tiny particles from the air. Blinking pushes this mixture toward the inner corner of your eye, where it drains away through small channels connected to your nose. When you sleep, the drainage still happens slowly, but without blinking to move things along, the leftover material pools and dries out. That’s the crust you peel away each morning.
What Normal Eye Crust Looks Like
Healthy morning eye discharge is white or pale cream in color. It can show up in two forms: hard, flaky bits in the corners of your eyes, or a thin, slightly sticky film along your lashes. The amount varies from person to person and even day to day. A small amount that wipes away easily is nothing to think twice about.
When the Color or Amount Changes
The appearance of your eye discharge is a reliable signal of what’s going on beneath the surface. Dark yellow or green discharge that’s thick and sticky, especially if it makes your eyelids difficult to open, is a hallmark of bacterial conjunctivitis (pink eye). Watery or white, stringy mucus that comes with itching and redness points more toward allergic conjunctivitis, which can flare up seasonally or year-round from indoor triggers like dust mites, pet dander, and mold.
A noticeable increase in the amount of crust, even if the color stays normal, can signal a problem with the oil-producing glands along your eyelids. This condition, called blepharitis, creates a cycle: inflammation disrupts the meibomian glands, which then produce lower-quality oil. When that oily protective layer breaks down, your tears evaporate faster, leading to dryness, irritation, and even more crust.
Other signs worth paying attention to include pain, redness, or swelling in or around the eye, blurred vision, and sensitivity to light. Any of these alongside a change in discharge warrants a visit to an eye doctor.
Why Some People Get More Than Others
Allergies are one of the biggest factors. If you’re sensitive to dust mites or pet dander, your eyes may react overnight while you’re face-down in pillows and bedding, producing extra watery or stringy mucus by morning. People with chronic dry eye also tend to accumulate more crust because their tear film isn’t functioning efficiently, leaving behind more residue.
Contact lens wearers sometimes notice more buildup, since lenses can irritate the surface of the eye and stimulate extra mucus production. Sleeping in a dry or dusty room, running a fan or heater overnight, and not removing eye makeup before bed can all increase the amount of gunk you wake up to.
How to Clean It Safely
The simplest approach is a clean, warm washcloth. Wet it with warm (not hot) water, hold it gently against your closed eyes for 30 seconds or so to soften the crust, then wipe from the inner corner outward. Use a different section of the cloth for each eye to avoid transferring anything between them. Avoid picking at dried crust with your fingers, since this can scratch the delicate skin around your eyes or push bacteria into the eye itself.
If you deal with consistently heavy buildup or crusty, flaky eyelids, a warm compress held against closed lids for five to ten minutes can help soften the oils in your meibomian glands and improve their output over time. Pre-moistened lid wipes, available at most pharmacies, are another option for daily eyelid hygiene. For people with blepharitis or recurring irritation, making this part of a nightly routine can reduce morning symptoms significantly.