French philosopher Gaston Bachelard wrote in 1960 that "sleep opens within us an inn for phantoms." Recent research agrees, finding that some sleepers shriek or even gorge themselves without knowing it. These sleep-disorder sufferers experience neural glitches that mix conscious and unconscious states. Scientists are now searching for the physiological underpinnings in hopes of developing better drug therapies.
Launch our gallery of the most bizarre parasomnias here.