It's a thing of common sense that if you read, drive or look at computer screen for too long your eyes will get tired. They burn, itch and try to close all the time. But I was wondering which part(s) ...
Why do our eyes close when we sleep? Is it to relax our eye muscles? How can it be explained from an evolutionary point of view?
It's a fact that some people sleep with their eyes open, but why does that happen? Is it normal behavior, not a symptom of any sort of disorder? Are there any (dis)advantages to sleeping with eyes ...