system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When you open someone's eyes while they're sleeping, why don't they see you and immediately wake up?

I used to do this to my dad while he was sleeping on the sofa when I was a little kid. His eyes would just kind of blankly look at me with this weird, cloudy, empty look. Why didn't he wake up?

I was a creepy kid...
gpt
The eye doesn't do the seeing. The eye is just the thing that takes in light, bounces it off the optic nerve, and sends that message to the brain. The brain is what does the seeing. It takes in the electrical impulse and translates that into what you understand as a visual image. Unless it is asleep. Then it isn't taking in impulses, it is sleeping. No impulse, no image.