Humans throughout history have described a peculiar state between wakefulness and sleep during which they are consciously aware of their surroundings, but physically paralyzed. Sleep paralysis is also commonly accompanied by high levels of fear, feelings of suffocation, and hallucinations (i.e., waking dreams). Early interpretations of this event were that it was an actual attack by malevolent and supernatural entities such as demons, ghosts, or witches. Some of these beliefs persist to the present day in the form of nocturnal visitations by extraterrestrials and shadow people....