What is sleep paralysis?
Sleep paralysis is is described as when a person seems to wake up during sleep but is unable to move. It is often accompanied by nightmares. Those who experience it may also have hallucinations or see shadows. This phenomenon is largely responsible for fueling tales of alien abductions. Nightmare “visits” are similar across cultures: Those afflicted experience the strange feeling of being “awake”; they can perceive their environment but can’t move. Many experience overwhelming fear and dread, accompanied by chest pressure and difficulty breathing.
How many people experience sleep paralysis?
It’s difficult to say for certain. Surveys from different countries around the world show a wide range of estimates. They suggests that anywhere from 20% to 60% of the adult population has experienced sleep paralysis at least once. Of these, around 5% have experienced one or more other disturbing symptoms coinciding with this, such as visual hallucinations, sensations of terror, or seeing shadows. (French, 2008) Some people may also feel pressure on their chest and have difficulty breathing, which combined with the hallucinations, leads some people to say they are convinced that the devil was sitting on their chest and trying to squeeze the life out of them.
What causes sleep paralysis?
During REM sleep (or dream sleep) a person’s brain keeps their muscles paralyzed. This is presumably designed to keep a sleeper from physically acting out their dream. It wouldn’t be good if we were all wandering around swinging baseball bats or walking to the store while unconscious and asleep. For reasons unknown, sometimes a person will gain consciousness during this period while other parts of their brain are still in sleep mode. This creates an “out of sequence” REM state, in which a mix of brain states that are normally separated from one another occur simultaneously. The result is that they feel awake but yet are unable to move or talk, which can be a rather scary and helpless feeling.
How long does sleep paralysis last?
Since most episodes of sleep paralysis last only a few seconds. But some people report experiences that last a few minutes or even longer. These claims are hard to verify, however, since time distortion is also common amidst altered brain states such as this.
Is sleep paralysis dangerous?
Normally no, but if a person panics, it is possible to literally believe themselves to death. Studies have documented panic-induced heart failures in people who are literally scared to death while riding roller coasters or experiencing an earthquake. Deaths seemingly linked to sleep paralysis have also been documented, especially in people from cultures with strong beliefs tied to these episodes. This phenomenon is referred to as SUNDS for Sudden Unexpected Nocturnal Death Syndrome, and at least several hundred cases have been reported. (Madrigal, 2011)
However, the condition itself is not medically dangerous, and deaths are very rare. More common (yet still unlikely) is the potential for such experiences to induce PTSD in a person. If these episodes are accompanied by feelings of terror or scary hallucinations, they can be just as traumatic as any real-world experience.