I've had it happen a handful of times in my life. The first time, I remember vividly. Hot summer night, lying on my stomach with the window open. The 11:00pm news was just coming on the TV, when I first sensed this malevolence. Then I realized I couldn't move. I tried desperately, while being aware of the room and tv noises. When I finally burst free, I did so with quite a shout. Freaked my poor mother.
At that time in the 70s, no one I knew experienced anything like that and I didn't have the advantage of the internet. So was on my own to figure that one out as a child.