Someone told me that happened to him, but he "resisted." Maybe not the same thing as you're talking about. I don't believe it either way. Well, the dude that posted on it described it as 'a dark cloud, with red orbs imbedded in it, with two armlike appendages'. He never said what it was called, but he said it was reported world wide, about dark cloud monsters paralyzing people while they sleep on their back or something.