The yellow goop that forms in the corners of your eyes after waking up is commonly known as “sleep” or “eye discharge.” This discharge is a mix of mucus, oils, dead skin cells, and, as explained by Andrew Huberman, dead bacteria.

Your eyes produce mucus and oils to keep them moist, and since you don’t blink while sleeping, this material accumulates in the corners of your eyes. The yellowish color usually comes from dead bacteria your eyes fought off during the night.

This is completely normal and is your body’s way of clearing out buildup from sleep. However, if the discharge is excessive or accompanied by redness, itching, or burning, it could be a sign of an infection, like conjunctivitis (pink eye), which may need medical attention.

Huberman compares it to “casualties of a war” fought while you sleep, which might make you see it in a new light—your body is working hard to keep your eyes healthy!