”People, especially when they are hypnotized, can easily weave together images, dreams, fantasies and things that they might just have heard or read about into elaborate pseudo-memories that they are confident are real,” Professor Newman said in an E-mail interview.
So what is sleep paralysis?
Even after many years of study, particularly in the last decade, it remains mysterious. Experts have trouble even saying definitively whether a person is asleep or awake during sleep paralysis.
”In the classic definition, you are awake,” said Emmanuel Mignot, director of the Center for Narcolepsy at Stanford University Medical School. ”But in practice, there’s a gradient between being awake and being in REM sleep,” he said, adding that sleep paralysis lies in a murky place on that slope.
During REM sleep — the period when rapid eye movement takes place — the body essentially turns itself off and disconnects from the brain. This is a safety measure, so that people do not physically act out their dreams, and it means that people are effectively paralyzed during part of their sleep. Even automatic reflexes, like kicking when the knee is tapped, do not work during REM sleep.
Sleep paralysis seems to occur when the body is in REM sleep and so is paralyzed and disconnected from the brain, while the brain has emerged from sleep and is either awake or semiawake. Usually after a minute or two the spell is broken and the person is able to move again, as the brain and body re-establish their connection.
Just what is going on in the brain during sleep paralysis is unclear. The person experiencing the paralysis certainly feels completely awake and ”sees” the room clearly, but laboratory experiments in Japan show that sometimes people experiencing sleep paralysis do not even open their eyes.
Sleep paralysis sometimes runs in families and appears to have a genetic component. Although it is normally harmless, some scholars believe it may be linked to a pattern of unexplained deaths among Hmong and other groups in Southeast Asia. The victims are usually healthy young people who die in their sleep, sometimes after fighting for breath but without thrashing around, and their faces show grimaces of terror.
