At first, you can’t move. It feels like you’re waking up, except your arms and legs and head and tongue are all frozen in place. You want to cry for help, but you can’t. You’re betrayed by your body, paralyzed. You lie there as your breathing begins to quicken, your heart rate jolting, until you see it: a shadowy figure in the room, moving closer. Maybe it’s a man in a dark cloak. Or maybe it’s an old woman, grotesque and witchlike. Either way, there is something sinister—and you are there, in your bed, powerless to do anything.