system
Given the following post, respond as if you're commenting on Reddit:
human
Why do our eyes become red when we are deprived of sleep?

It's a classical sign. Why does it happen?
gpt
When the small blood vessels on the surface of the eye (sclera) become enlarged and congested with blood, as a result of insufficient oxygen supply to the cornea or the tissues covering the eyes, the eyes can become red. Sleep deprivation, alcohol, and decreased tear secretion at night can all contribute.