Waking up with “crusty eyes,” often called “sleep crust” or rheum, is a widely experienced phenomenon. This eye discharge is a natural byproduct of the eye’s continuous self-cleaning process. Rheum consists of mucus, oils, dead skin cells, and tears, which the eyes produce to maintain their health and remove foreign particles.
Normal Morning Eye Crust
During the day, your eyes are constantly lubricated and cleaned by tears and blinking. Each blink acts like a windshield wiper, spreading a protective tear film across the eye’s surface and flushing away small particles, dust, and excess mucus into the tear ducts. This continuous action prevents debris from accumulating and drying on the eye’s surface.
At night, the blinking process significantly reduces or stops altogether during sleep. While you sleep, your eyes continue to produce tears, oils, and mucus, but without regular blinking, these substances are not washed away. Instead, they gather in the corners of the eyes and along the lash line. As the night progresses, the watery components of this mixture evaporate, leaving behind a dried, crusty residue. This accumulation is a normal and healthy indication that your eyes have been effectively cleaning themselves overnight.
Medical Reasons for Excessive Eye Crust
While some morning eye crust is normal, an excessive or unusual amount, or a change in its consistency or color, can signal an underlying medical condition. These conditions often lead to increased discharge production or hinder its normal drainage.
Conjunctivitis, or pink eye, causes inflammation of the conjunctiva, the membrane lining the eyelid and eyeball. The type of discharge varies: bacterial conjunctivitis often presents with thick, sticky yellow, green, or gray discharge that can glue eyelids shut, especially in the morning. Viral conjunctivitis typically results in clear, watery discharge, sometimes accompanied by a gritty sensation. Allergic conjunctivitis, triggered by allergens like pollen, usually produces clear, watery, or stringy white mucus, alongside itching and redness.
Blepharitis involves inflammation of the eyelids, often at the base of the eyelashes, and can cause flaky or greasy crusts along the lash line. This condition can make eyelids appear red, swollen, and itchy, and may result in eyelids sticking together. It stems from issues such as bacteria or clogged oil glands.
Dry eye syndrome occurs when the eyes do not produce enough tears or when tear quality is poor. Dry eyes can lead to compensatory overproduction of mucus, resulting in stringy or crusty discharge. The imbalance in the tear film can also cause discomfort and light sensitivity.
Allergies can increase eye irritation and watery discharge that dries into crust, and are a common cause of allergic conjunctivitis. Blocked tear ducts prevent tears from draining properly, leading to watery eyes and a sticky white or yellow discharge that can become crusty. This can also increase susceptibility to eye infections. Localized infections like styes or chalazions, blockages or infections of eyelid glands, can cause localized crusting around the affected area.
When to Be Concerned and What to Do
Certain symptoms associated with eye crust warrant medical attention. If the eye crust changes color to green or dark yellow, significantly increases in volume, or makes it difficult to open your eyes, it could indicate an issue. Other concerning signs include eye redness, persistent itching, pain, swelling, sensitivity to light, or blurred vision. If any of these symptoms are present, or if the crusting is bothersome and does not resolve, consulting an eye care professional is advisable.
For self-care, maintaining good eye hygiene can help manage normal eye crust. Always wash your hands thoroughly before and after touching your eyes. To remove crust, soak a clean washcloth in warm water and gently place it over your closed eyelids for a few minutes to soften the discharge. Then, gently wipe from the inner corner of the eye outwards.
Avoid rubbing your eyes vigorously, as this can introduce bacteria or further irritate the eyes. It is also advisable to avoid sharing eye makeup or towels to prevent potential spread of infection. Contact lenses should be removed before sleeping, and thorough makeup removal before bed is also beneficial.