system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What's happening when you hear a noise while falling asleep and you see a flash of light even though you're eyes are closed?

This happens to me from time to time. I'll lay down to go to sleep at night. I don't keep a TV in my room so it's silent and completely dark. During that time where I'm in between being asleep and awake but still kind of aware of my surroundings I'll hear a sudden noise that's unfamiliar, maybe it's a creak in the house or something outside that startles me. When this happens I see a flash of white light even though my eyes are closed and there was no light that came on. What is happening here and why does it happen?
gpt
Im not sure what the effect is called specifically, but its just a simple hallucination.

Your brain cant handle "no information" so if times are dire, it makes its own.

You need nothing more than static or complete darkness for this.
If you have ever experienced total darkness you know what im talking about, you see lights and colour everywhere after a certain amount of time.

After all, your brain is constantly calculating and manipulating the source data (what your eyes send) and its not even close to what you actually sense.
(You have two constant blind spots, you are seeing everything upside down etc) so its no big surprise that "no information" kind of confused the brain a bit.
(the sound could be a hallucination as well, i get those a lot when its silent and im about to sleep)