system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What purpose does eye movement serve during REM-sleep?
gpt
It's more of a response to REM.

During REM sleep, the visual cortex of the brain is “awake,” just as it would be during an awake state.  
 Sleep researchers believe that the eyes may be working to focus on an   
area “seen” in a dream, but more research needs to be done in this area.  
 People who are blind experience REM sleep the same as people without   
visual disabilities.

Some researchers believe that REM sleep doesn’t actually correlate with dreaming,  
 rather, the eye movements experienced during REM sleep have to do with   
the brain’s memory processing. Others believe that the eyes are   
“exercising” during this time, toning the muscles that are used to move   
the eyes during the day.