system
Given the following post, respond as if you're commenting on Reddit:
human
Why do we see colours and 'stars' when we close our eyes?

What is the brain doing that makes us see the random swirling colours and spots when we close our eyes but are still awake?
gpt
That's what we call "visual snow." In your visual nervous system, there is a small baseline level of neurological activity going on, even when you're not getting a stimulus. Basically it's just random firing of a few neurons here and there. Usually this activity is washed out by all the visual information you're getting from your eyes. 

Think of it like a radio that's just a tiny bit out of tune. Normally, when the music is playing, you wouldn't hear the small amount of static that's there. Once the music stops, however, you can hear the static. It's the same thing with your eyes. When you close your eyes, you've eliminated the external stimulus (the "music"), and all that's left is the baseline neurological activity (the "static").