I had episodes of this as a kid, not demons or anything that specific, but thinking I was awake and some weight was on my chest, just as they describe. I figured it was a dream but very terrifying at the time,
I had episodes like that when I was a kid as well, and strangely enough, I called them “demon dreams” because they were terrifying. Mostly, it was knowing I was asleep but unable to wake up, even though in the dream I would be trashing around, screaming, etc.
Later, I learned that the only muscle that is not paralyzed when you have those episode is your tongue and jaws so I whenever I had them, I would manage to bite my tongue hard enough for the pain to intrude and wake me up. Haven’t had one in 20 years or so.
Still spooky.