I've heard of something called open eye dreaming or something

It's the main explanation for people who claim to have been abducted by aliens.

The way those people describe abduction is they wake up and cannot move a muscle and cannot say anything. Then they may experience strange sounds or see bright lights and see an alien like being, that they can feel touching them and taking them away for a night of anal probing.

This is explained by docters as sometimes when you go from awake to sleep your eyes can open up. So your body will be asleep and your mind will be going deeper and deeper into sleep, but with your eyes open. So people can start off with just being in there room not being able to move to flying around in space with ET.

But of course it's not just for aliens, you could be dreaming of anything with your eyes open.