I used to have this shit often when I was in college, eventually I learned that you can still wiggle your toes for some reason, and by doing so you slowly regain control of your body. It sucks still, that feeling of paranoia, that weird buzzing sound inside your head, the feeling of being pulled into something that you can't quite tell what is but you know it's bad so you fight to remain half-awake and the hallucinations, they're horrible.
I remember seeing something in my room once, it was a black humanoid figure with glowing white eyes, just sitting on my bed looking straight at me, and I also remember feeling the bed "sinking" under the thing's weight. It's crazy!