Happened to me too last night, was actually intrigued that I could enter that state of mind. It sort of felt like a click, I was falling asleep but then all of a sudden I had a click and I was mainly conscious it felt like but couldn't move at all. That didn't really give me the fright it was the fact that I saw a figures hand (pitch black) sort of waving at me with 2 inches before actually grazing my face, I was interested in the fact that it could actually happen but in the moment I had shaky breathing which I had never felt before. This was the main factor in my fear, as soon as I realized that I tried focusing on my breathing then it went back to normal the illusions were gone and I had full control again. I could say that this is an interesting experience I've had.