Occasionally I have these nightmares where... I don't think it quite fits the bill of sleep paralysis, at least not the "classic" concept of it. But nightmares where I realize that I am dreaming and I repeatedly try to wake up, but every time I 'wake up' I end up back in my bed. Usually I feel extremely heavy, like I'm being pulled down, and it's hard to keep my eyes open in the nightmare. Everything around me is dark/weird, usually sounds like inside a seashell. Sometimes in the nightmare I manage to drag myself out of bed, falling down repeatedly like there's something heavy pulling me down--but no matter how far I get, I end up back in bed again and again. Sometimes I make it all the way to the other end of the house to the other bedroom, when when I go to wake them up they can't hear me no matter how hard I scream. A few times the waking up repeatedly in the nightmare goes on so long that when I do wake up for real it takes me a while to believe it.

Once or twice I've gotten up during these nightmares and walked down the hallway, where I wake up, usually in the process of kneeling/falling down. But not usually.