Reading this this morning, it is freaky - I had such an episode last night - the first one in years and probably about the 4th or 5th one ever. It felt like someone pulling on my arms, trying to move my body - as though a 'spirit' is trying to take me away. I try to cry out or scream but nothing comes out. Then I kept feeling arms around my waist - the feeling was very real & weird. Eventually I think I did manage a 'no' and it left me alone - but it always leaves me very shaken for the rest of hte night.
The first time I had it, I was told by some well-meaning soul (not) it was an incubus and it was trying to lay on top of me and have sex with me - now I looked up what an incubus was & it scared the life out of me. Then I saw a film not long afterwards, called Entity - which was a similar story about a woman being raped by an incubus. It took me ages to get over that, & I was terrified of it happening again.
I think now I accept it as sleep paralysis or a night terror - but they are very realistic and frightening.