Not every dream is pleasant; many are disconcerting or even terrifying. Unpleasant dreams—particularly those that are frightening or deeply upsetting—are referred to as “nightmares,” and are ...

Night hags and night mares. Succubi and incubi. Sleep has long been a demon-haunted world. In olden days such visitations were thought to drain the dreamer of life-energy and, though modern science ...