The effin weirdest thing just happened to me as I was taking a nap:
And like, I've seen inception.. sooo idk? That helps too.
But generally, the gist that I got from it is that you accidentally get into this awakened state during REM sleep, and even though you aren't awake - you feel awake, and you aren't dreaming anymore. But your brain keeps the dream state going. So you start fighting the brain to move and get up, but you are paralyzed. They hypothesize this is so you don't sleep walk or act out the dream you are having.
this video by Michael Shermer (skeptic extraordinaire) about a year ago, and knew in the back of my mind that the brain is responsible for making you feel and see ghostly spirits. And because I was feeling awake, I was like okay yeah, clearly my brain is doing something weird.
But this whole "ghostly encounter" is quite normal. Most people experience it as part of sleep paralysis. They literally feel held down. I know I felt that, and that could explain why I couldnt even yell out. But it is, like Michael Shermer said, your brain acting out some crazy stuff - and because you are in dream state still, it feels really real.
Anyway, I don't really have much more to say... Just thought I would share my experience. If you have stories about this, post them here! I am very curious!