What a difference a hyphen can make. A nightmare is, as you know, a bad dream, the experiences we all have while sleeping that fuel feelings of fear, anxiety, sadness or other negative emotions. A night-mare, however, is much more specific, powerful and horrifying, as it’s another name for sleep paralysis: a unique state between consciousness and unconsciousness in which you can’t move or speak but your eyes are open and you experience very vivid hallucinations of a malevolent force in the room with you that exerts pressure on your chest, causing you to gasp for breath.
Sleep paralysis affects a minority of the population, but it’s a global phenomenon that’s probably as old as humanity, as evidenced by the fact that it’s been referenced in books, art and folklore…