This week's issue of Science News explores the creepy world of sleep paralysis, a mental phenomena where someone is about to doze or off or is just waking up and suddenly becomes unable to move. Many scientists believe that sleep paralysis is the biological answer to such mysteries as spirit visitations, alien abductions, incubi/succubi, and out-of-body experiences. (Painting is "The Nightmare" by Henry Fuseli, 1753.) From the article:
In the past 10 years, psychologist J. Allan Cheyne of the University of Waterloo in Canada has collected more than 28,000 tales of sleep paralysis. According to one of the chroniclers, "The first time I experienced this, I saw a shadow of a moving figure, arms outstretched, and I was absolutely sure it was supernatural and evil." Another person recalled awakening "to find a half-snake/half-human thing shouting gibberish in my ear." Yet another person reported periodically waking with a start just after falling asleep, sensing an ominous presence nearby. The tale continues: "Then, something comes over me and smothers me, as if with a pillow. I fight but I can't move. I try to scream. I wake up gasping for air."
Many who experience sleep paralysis also report sensations of floating, flying, falling, or leaving one's body. The condition's primary emotion, terror, sometimes yields to feelings of excitement, exhilaration, rapture, or ecstasy. "A small number of people, while acknowledging fear during initial episodes of sleep paralysis, come to enjoy the experience," Cheyne says.