A respondent in the Guardian article I linked to above often experiences multiple episodes of sleep paralysis a night. Not all of them are unpleasant - occasionally, he says, there's a sexual element - but it all sounds rather trying:
Common images are bearded, goblin-like demons laughing or whispering sinister speech, a faceless girl (usually covering her face with hair, moving around in bed moaning and feeling my body), hands appearing from the wall and attempting to strangle me. A hung man talking in the corner of the room, and some of the most bizarre experiences may include up to a dozen 'critter' entities (think Gremlins movie) laughing and talking about me.
I'm not sure whether he means a hanged man talking in the corner of the room, or whether that was one of the sexual episodes.