Ha. Actually the exploding head syndrome is real. (wikipedia link)
Its what gets mistaken for the old hag syndrome. Old woman screaming or whatever, making you paralyzed, sucking out your chi energy or destabilizing your meridian flow – pick your favorite psychic nonsence gobeltygook, or aliens abducting you.

I got this once while nearly asleep, I was paralysed, and then I heard an utterly deafening roar go through my head. I thought it was god here to smite me for being such an atheist asshole. It was terrifying. Having nearly soiled the pants I woke up, regained full consciousness, and goggle’d a bit, and found this to be a documented phenomenon. So that counts out the god hypothesis. Still, this is what all those old hag / alien abduction stories are based upon usually.