Ok, this has happened a few times:

I'm overtired, about to fall asleep, and then I enter sleep paralysis (without wanting to). Then I start to panic. I try to move my fingers in order to get out. Then I kinda get control of my arm and can slowly move it (but it's really difficult). Then I'm also able to kinda move my head a bit. But the strange things is, when I move my head, I just see a still image, nothing moves even thought I move. I can feel when I'm turning my head and arms, but I just see a still image. Quite scary.