The sticky substance found in the corner of your eyes upon waking, often called “sleep crust” or “eye gunk,” is medically known as rheum. This material is a natural byproduct of your eye’s constant self-cleaning process, and a small amount is considered normal. If you wake up with your eyelids completely stuck together or notice a significant increase in discharge, it may indicate a deeper issue requiring attention.
The Physiology of Sleep Crust
The eyes continuously produce a combination of mucus, oil, and tears to keep the surface lubricated and clean throughout the day. This mixture contains exfoliated skin cells, dust, and other debris collected from the environment. While you are awake, blinking spreads this tear film across the eye and directs the debris toward the tear drainage system, preventing accumulation.
When you sleep, the eyes are closed and blinking ceases for several hours. Without the sweeping mechanism of the eyelid, the debris collects in the inner corners of the eye and along the lash line. As the water component of the tears evaporates overnight, the remaining components, particularly the mucus and oil, dry and form the familiar sticky, crusty material.
Non-Infectious Reasons for Excessive Build-Up
An increase in morning stickiness frequently signals an irritated ocular surface attempting to protect itself. A common non-infectious cause is Dry Eye Syndrome, where the eyes produce insufficient or poor-quality tears. In response to dryness, the eye’s surface cells overproduce the mucus component (mucin), resulting in thick, stringy discharge that is noticeably stickier than normal rheum. This compensatory mechanism attempts to add moisture to the compromised tear film.
Allergic reactions are another frequent cause, often leading to significant white, stringy, or watery mucus. Allergies cause intense itching, redness, and swelling in both eyes simultaneously. Environmental factors, such as sleeping near a harsh air conditioner or in a room with very low humidity, can also cause excessive stickiness. These conditions exacerbate tear evaporation overnight, leading to a drier eye surface and a subsequent increase in mucus production.
Identifying Stickiness Caused by Infection
When eye stickiness is accompanied by severe symptoms, it may signal an active infection, such as conjunctivitis or blepharitis. The most concerning sign is a change in the color and consistency of the discharge. A thick, opaque, yellow or greenish discharge that completely glues the eyelids shut upon waking strongly indicates a bacterial infection. This discharge is a mucopurulent exudate, containing white blood cells fighting the bacteria.
Viral infections, which are often associated with a common cold or flu, typically produce a clear, thin, and watery discharge that may still cause crusting. Unlike the thick pus from a bacterial infection, the viral discharge is more profuse and less sticky. Other red flag symptoms requiring immediate medical evaluation include severe eye pain, extreme light sensitivity, or any sudden decline in vision.
Simple Management and Prevention Steps
Managing morning stickiness often involves simple changes to hygiene and environment. If you wake up with crusty eyelids, the safest way to loosen the material is by applying a clean washcloth soaked in warm water as a compress. The heat softens the dried rheum, allowing it to be wiped away gently without irritating the delicate skin. Never rub the discharge away with bare fingers, which can introduce bacteria and worsen irritation.
Regular, gentle cleaning of the eyelids with a mild cleanser helps prevent the nighttime buildup of oils and debris that contribute to crusting. Using a humidifier in your bedroom can also reduce the dryness that triggers compensatory mucus overproduction. If these steps do not alleviate the stickiness, or if symptoms like pain, redness, or colored discharge persist, professional medical consultation is necessary.