You know that dream where you’re naked in front of all of you classmates or at work? What about the one where all of your teeth are falling out of your head? In Persian mythology, these and dreams like them are blamed on a creature called Bakhtak. This invisible creature sits on the chest of its victims, turning sweet dreams into nightmares and, in some cases, causing sleep paralysis. This should ease the minds of scared children when they run into their parent’s room at night. “Don’t worry Jonny, it was just a dream caused by an invisible demon creature who sits on your belly while you sleep!”