I've had this happen to me a lot when I was younger. The first time it happened I was convinced it was a wrap, lol. I didn't know what I was struggling against, but I had this feeling that if I stopped fighting, I would never get another chance, again. As I've gotten older, it only happens a handful of times a year. Still the woat feeling. It feels like something is pulling me through my bed. I joke with myself that I'm getting early access to my trip to hell, lol.
Also, many people I've spoken to irl and online have all mentioned encountering some kind of entity, too. Either "shadow people" or "a woman". I've thankfully never experienced seeing any shadow people, but there was one time in particular where I encountered the woman/the hag. I'll never forget it, I was lying on my side and completely frozen. At that point in my life, it already happened so much that I wasn't panicking too hard, just waiting for it to pass. Next thing I know, I feel goosebumps down my neck and then I start hearing a woman laughing. A quiet, but malevolent laugher. To this day I don't know what it was. I was convinced she/it was right behind me, breathing on my neck. Like others have mentioned, I tried to scream, but nothing came out.
Some people say it's a holy spiritual experience, others say demonic. Some that it's related to astral projection and lucid dreaming. Meanwhile, scientists believe that it happens because the mechanism in our brains responsible for turning off motor functions in your sleep (so that you don't physically act out your dreams) activates before we are actually asleep. I don't know what to make of it, anymore.
As terrifying as it is, it's undeniably an interesting experience for sure, though.