Wow, this is a neat topic! I've never experienced sleep paralysis-thank God, but i know many people that do and they say if they say a prayer it usually snaps them out of it. 'I've heard sleep paralysis referred to as 'the devil riding your back' anyone else ever heard of such?
The people that i know who have experienced it says it's like an evil presence standing over them and they can't scream, move or anything! I do recall them saying that it mainly happens if they sleep on their back.
Next time it happens try saying a prayer and see if it works.
Good luck and God bless.