See, I had this nightmare last night. And it was a real doozy because it was a Sleep Paralysis nightmare. Those aren't the normal ones where you get chased by a monster or something. Oh no. If only it were that easy you could just wake up.
See, in a sleep-paralysis nightmare you're already half-awake. You can sort of see the real world, but you have no idea what's going on, like in a dream...only this nightmare has something most don't.
Because there's someone, or some thing, in the room, in the real-world room, with you.
It's usually a dark shape, vaguely humanoid. There but not there.
What it really is, is a mental manifestation of a temporary breakdown in the part of your brain that registers the presence of other people. Kind of like seeing the burned-out area on an old film reel. So it's a hallucination. Only, you're only half-awake so you can't even begin to grasp that fact, and in the meantime you're stuck in sleep paralysis so you can't move away from the damn thing, or even cry out for help. You're trapped in its supposed presence, unable to do anything but feel terror. This mental breakdown frequently accompanies sleep paralysis, and it's the origin of German tales about elfs sitting on the chests of sleeping people to steal their breath.
And that was my situation, last night. Something opened a door next to my bed (a door that wasn't there) and sat down and...looked like it was reading a newspaper? I was too scared to laugh, and too confused about why I couldn't move.
The nightmare ended when I managed to roll over. Scariest 30 seconds I've ever had.
(I just realized that this sounds like it would fit in the Halloween Horrorquest. Hello, ghouls and goblins, it is I your friendly ghost.)