edit: You wake up, but you canít move a muscle. Lying in bed, youíre totally conscious, and you realize that strange things are happening. Thereís a crushing weight on your chest thatís humanoid. And itís evil. You might have even felt afraid but could not call for help. This condition is called sleep paralysis. Sleep paralysis may leave you feeling frightened, especially if you also see or hear things that aren't really there. Sleep paralysis may happen only once, or you may have it frequently -- even several times a night.
I wasn't going to comment but decided against it since this's my frequent condition. I actually get this a lot, and like you said, sometime I have this the whole night long. Wake up with this, then really wake up, fall asleep again because I was too tired, and get this again. All night long.
In my country, they call this 'bóng đè' or 'ma đè', basically means 'a shadow lying over you' or 'a ghost lying over you'. I also happen to have something with my 'spiritual energy' that actually welcome ghosts.
I've been living with sleep paralysis for four years. So I feel your fear, hey.
It was just a black shape of a man, nothing special, but by god it scared the living shit outta me when it came closer until it almost touched me, he never really did touch me though, he keeping looking at me and the spot he was going to touch before I finally forced myself to sleep.
And I know this horribly feeling very well.
I have this until know about six times I think. One time I remember very well, I dreamed that where under water and I can't breathe and I tried to open my eyes, or move my body, but it haven't worked at all. I have no feeling for time, as this happened, but I it endet, as the noise, that I've heard, endet :/ I really never forget this creepy moment.