Sleep paralysis is a state in which a person is aware but temporarily unable to
move or speak when falling asleep or upon awakening. This
state lasts only a few seconds to minutes, but it can be terrifying. Sleep
paralysis is often a symptom of narcolepsy, an ongoing condition marked
by excessive sleepiness. Sleep paralysis without narcolepsy is
referred to as isolated sleep paralysis. Sleep paralysis often occurs during daytime naps or when a person
is jet-lagged or otherwise deprived of
sleep. Jet lag is a travel-related condition in which the natural cycles of
sleep and waking become out of step with local time.
Common sensations that occur
during sleep paralysis include feeling of floating outside one’s
body. Another common and frightening occurrence is the sensation that another
person is in the room. This figure may appear as a dark shadow, or the
paralyzed person might simply sense a
malevolent presence. You may also dream an intruder with feature of a demon, a witch, or a creature with sharp
teeth and cat-eyes. In the sleep paralyzed state, a person may have the feeling
of being attacked, choked, or suffocated by the intruder.
Cause. Sleep paralysis happens when a
person wakes while still in a stage of sleep called rapid eye movement (REM) sleep. REM sleep
is the stage of sleep in which vivid dreams occur. During REM sleep, a part of the brain called
the dorsolateral prefrontal cortex becomes inactive. This
portion of the brain is central in the ability to plan and think logically. It
is this inactivity that enables the fantastic things that occur in dreams to
During REM sleep, the body is paralyzed by the
brain. This paralysis prevents the person from being hurt by acting out or
moving while dreaming. Sometimes, however, people do wake up while the brain is
still in the REM state. This occurrence may leave the person stuck in a
borderline state of consciousness between sleep
and wakefulness while the body remains paralyzed. Occasionally during such sleep
paralysis, the vivid and sometimes frightful or threatening dreams of REM sleep
can intrude into waking consciousness. In effect, the person is dreaming with
Occurrence. Experts believe that around 20 to 40 percent of people experience
isolated sleep paralysis at least once in their lives. The condition runs in
families and is common in all cultures throughout the world.
Cultural significance. Sleep paralysis and its effects
are rooted in folklore related to nightmares.
The term nightmare comes from the Old English word mare, a kind of female evil
spirit or goblin.
In European folklore, this
spirit was said to sit on a person’s chest during sleep, causing bad dreams.
sleep paralysis has sometimes been seen as an assault by the pandafeche, beings
described as witches or catlike creatures. In Newfoundland, it is referred to
as an old-hag attack. Among
Egyptians, some believe sleep paralysis to be caused by supernatural creatures
known as jinn. In the
United States, sleep paralysis may be responsible for some reports of abduction