Many cultures have stories about a Sandman who puts people to sleep by sprinkling sand in their eyes. In the morning, they wake up and rub the crusty sand from their eyes. In reality, this “sand” is eye discharge that collects in the corners of our eyes while we sleep. There are many causes of eye discharge, though it is generally harmless. Types and colors of eye mucus can also indicate various causes or conditions.
Though we may only notice it after waking up, healthy individuals are always creating eye discharge consisting of mucus, skin cells, oil, and other debris. While we’re awake, constant blinking washes away eye discharge through the tear ducts. But humans don’t blink while asleep, so eye discharge accumulates at the edges of the eyes. Eye infections, eyelid inflammation, and styes can change the appearance of eye discharge.
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