The study, reported in Monday's issue of Neurology, is part of an ambitious project examining the prevalence of sleep disorders in people 15 and older in Great Britain, France, Italy, Germany, Spain, Portugal, Norway, and Finland. Sleep paralysis is associated with sleep deprivation and mental disorders such as depression or anxiety. Of those participants experiencing sleep paralysis, users of anxiety-reducing medications were five times more likely to report incidences of the phenomenon. Sleep paralysis is also associated with daytime sleepiness, as well as narcolepsy, a disorder characterized by irresistible sleep attacks of five to 30 minutes during waking hours. These attacks can occur without warning and at inappropriate times.
Experts think sleep paralysis is a manifestation of rem sleep.
We all experience rem, the dream state around four times a night, during which time we are paralyzed. Most people never realize they have it. But for it to occur, a pathway in the brain stem and spinal cord is activated, and this pathway may be slightly malfunctioning during sleep paralysis. In narcolepsy, the muscles are abruptly turned off as in the rem state. And experts in the sleep field think the same pathway may be disrupted in sleep paralysis as well.