Due to REM (Rapid Eye Movement or during the dream phase) the central nervous system paralyzes the body. Only the pupils can move under the closed eyelids. This paralysis can sometimes last into the first moments of wakefulness: The mind is already conscious but the body is still in the state of sleep.
Sleep paralysis is a common phenomenon–up to 60 percent of people have at least one episode, in which the brain and body momentarily desynchronize when waking from REM sleep. The body remains paralyzed, as is standard during the REM cycle, but the mind is semi-lucid or fully cognizant of its surroundings, even, according to a Japanese study, if one’s eyes are closed. The experience can’t be technically classified as either waking or sleeping.
Occurring across cultures in approximately 15 percent of the population, sleep paralysis is sometimes accompanied by horrifying visual and auditory hallucinations: a sensation of electrical tingling or levitation, hearing buzzing noises, seeing flashing lights or shadowy figures hovering near the bed. The Japanese call it kanashibari, represented as a devil stepping on a hapless sleeper’s chest; the Chinese refer to it as gui ya, or ghost pressure.
Sleep paralysis with hypnopompic hallucinations (those that occur upon waking) can be so unexpected and terrifying that people routinely believe they’re stricken with a grave neurological illness or that they’re going insane. When faced with these prospects, aliens no longer seem so nefarious. But sleep paralysis and abduction don’t always go hand in hand.
Consider the case of “Janet,” a 52-year-old copy editor in Chicago. Eleven years ago she endured a terrifying out-of-body experience while lying in bed. Janet saw her head strapped in a vise as a group of men looked on. Fuzzy images were projected onto the back of Janet’s eyes, visions she likens to “a 3-D hologram engraving something into my head.” Her first thought on waking was of a brutal sexual assault she’d once read about. McNally believes it is the sense of powerlessness in being immobilized that triggers associations with invasive sexual procedures.
Janet experienced terror and helplessness in the wake of these messages she could not decipher, and sought the help of numerous therapists. But she says she “never thought this had anything to do with aliens. I thought it was something arising from the depths of my subconscious.”
Why, then, do some people who experience violent hallucinations upon waking or falling asleep conclude that they have been abducted? One possibility is that people embellish their experience in the course of hypnotic regression.