[jeffnc]

I have experienced what you're calling "sleep paralysis" as well. It's very not cool. My dad had it occasionally. It's only happened to me 4 or 5 times in my life. Quite an unpleasant experience, because it's usually initiated by something mildly scary while you're sleeping. For example, you hear some noise you think is coming from your window. You wake up, at first in a sort of dream state imagining all sorts of things that noise could have been. Then you're awake, unable to open your eyes, unable to speak or move, yet convinced (for example) that someone is trying to get in that window. (Note that you're not imagining something weird like a dragon trying to get you. You are imagining something completely plausible, like someone breaking into your house.)

Very disconcerting and unpleasant.