what does this mean?

sometimes when i'm tired and i'm lying down (usually for a nap) i know i'm still awake, my body is awake and my mind is awake but after a few minutes i get these random ass images in my head, the kind of shit that shows up in my dreams, and they just stay there for a little while, playing out some weird story. it also feels like my hearing is gone, and i kind of zone out for a bit, but i'm fully conscious.
does that make sense?

I know exactly what you mean. I swear the less sleep I get the night before the the more likely it is to happen.

I like to consider them dreams but I tend to forget about them instantly if somebody/something jolts me out of it.