Upon waking, many people commonly notice a small amount of crusty or sticky material in the corners of their eyes. This phenomenon, often referred to as “eye sleep,” “sleep crust,” “eye gunk,” or “eye boogers,” is a normal and routine part of how the eyes maintain their cleanliness. It is typically a harmless byproduct of the eye’s natural protective processes that occur overnight.
What Exactly Is It?
“Eye sleep” is the informal term for what medical professionals refer to as “rheum” or “eye discharge.” This substance is a natural accumulation that gathers in the corners of the eyes and along the lash line, particularly during sleep. Its appearance can vary, ranging from a hard, crusty, and sometimes yellowish material to a wet, sticky, or thin, watery consistency. The specific texture depends on how much of its liquid content has evaporated.
Components of Eye Sleep
Eye sleep is primarily composed of several substances produced by the eye itself, combined with environmental particles. It consists of mucus, which is produced by the conjunctiva—the clear membrane covering the white part of the eye and the inside of the eyelids. Alongside mucus, it contains oil, known as meibum, secreted by the meibomian glands located along the eyelid margins. These oily secretions help lubricate the eyes and prevent tear evaporation.
Additionally, eye sleep includes dead skin cells that naturally shed from the eyelids and surrounding skin. Environmental debris, such as dust particles, also contribute to its composition. These components combine and dry, forming the visible “sleep crust” that collects in the corners of the eyes.
The Purpose of Eye Sleep
The formation of eye sleep serves a protective and cleansing function for the eyes. During waking hours, blinking helps to spread tears across the eye’s surface, washing away foreign particles, excess mucus, and dead cells. Tears constantly bathe the eyes, flushing out these waste products through the nasolacrimal duct, preventing them from accumulating and hardening.
During sleep, blinking ceases, and tear production may decrease. Without the flushing action of blinking, the eye’s natural cleansing mechanisms work to gather accumulated debris. Mucus, oils, and other particles are pushed towards the inner and outer corners of the eye by the eyelids. Once collected, these substances dry and form the “sleep crust,” effectively removing potential irritants from the eye’s surface.
When to Seek Medical Advice
While eye sleep is usually benign, certain characteristics can indicate an underlying eye condition requiring professional attention. If the eye discharge is excessive, unusually thick, or has a distinct color such as green, yellow, or grey, it may signal an infection. Discharge accompanied by pain, redness, itching, or swelling of the eye or eyelids also warrants concern.
Other symptoms that suggest a potential problem include light sensitivity, blurred vision, or eyelids that are consistently stuck together throughout the day. These symptoms can be indicative of conditions like bacterial or viral conjunctivitis (pink eye), allergic reactions, or a blocked tear duct. For example, bacterial conjunctivitis often presents with sticky yellow or green discharge, viral conjunctivitis with watery discharge and redness, and a blocked tear duct can cause watery eyes and sticky discharge.
Maintaining Eye Health
To manage normal eye sleep and promote overall eye hygiene, gentle cleaning methods are recommended. Wash hands thoroughly before touching the eyes. To remove eye sleep, a clean, warm, damp cloth should be applied gently to the eyelids and eyelashes. This softens the dried crust for easy removal.
Vigorous rubbing of the eyes should be avoided, as this can cause irritation or introduce germs. Maintaining good personal hygiene, such as regularly cleaning makeup brushes, is also beneficial for eye health. These brushes can accumulate bacteria, dead skin cells, and oil, which can then be transferred to the eyes.