Well, one is never too old for new life experiences, I guess.
I went to bed last night, read for a while, then turned out the light to engage slumber mode. Then it happened, a thing that I had read about in books but never experienced. And, no, it wasn't that sort of book. Or that other one.
Infrequently, maybe a few times per year, just as I'm falling asleep, I have a 'tripping over the kerb' sensation, a leg shoots out to maintain my balance and I'm awake again. It wasn't that. But this morning I discovered that the kerb trip is known as a hypnogogic jerk. I've been called worse.
Nuh-uh, this was a whole other order of strange, but one from the same stable. I was suddenly aware that I couldn't move, not an arm or a leg, nothing. My vision felt as though I was looking through a large sheet of tiny bubble wrap, or a huge tv wall from a great distance. This gave way to some dancing motes of light, and when I realised that my eyes were closed, I opened them (so something could move), which made absolutely no difference to the view. I was wondering what the unseen presence to my left could be, as I could hear Our Lass breathing on my right, and just as I was thinking "Oo, I've read about this sort of thing!", I woke up.
So, sleep paralysis, wow!
Sadly, no succubus, but that was probably for the best, eh?
In less enlightened times (not that I'm suggesting that 'now' is particularly enlightened), there would have been all sorts of fantastical explanations for the experience. And plenty of weird reactions to it, some of which may have been more scary than the actual event. Somewhat prosaically, I suspect a rare mug of coffee, rather than possession, anything occult or plain old fruitloopery.