I agree with Pat, could be many things. My son has narcolepsy and catalepsy and one of the things he must deal with is sleep paralysis. Its a chemical thing in the brain. I know of one case where an entity did that to someone. Not a dark entity but one needing help in its journey out'a here. Dark entities can do that but as a mechanism to create fear, which is what they want. So I would recommend shielding and thinking positive thoughts ... be happy, dance and sing. Life is a wonderful gift.