Imagine waking up from a deep sleep … only you can’t open your eyes, speak, or move. Although your brain is awake and active, taking in everything around you, your body is totally paralyzed, unable to move. You might even imagine a crushing sensation on your chest, or sense an evil interloper watching you as you lie helpless.
Sleep paralysis has been capturing humans’ morbid imaginations since at least 400 BC, when the Chinese included a description of it in a book about dreams. The Greek physician Galen studied it, as did the historian Herodotus and the Roman poet Horace. It’s even the origin of the word “nightmare.” This strange and disturbing phenomenon is thought to affect between 25 and 40 percent of people in the world, and contrary to the old wives’ tales, bad vapors, evil spirits, and alien abductions do not cause it. Actually, it’s not even nearly as dangerous as it sounds.
Waking Brain, Sleeping Body
There are two different kinds of sleep paralysis. Predormital sleep paralysis occurs just as someone is just drifting off, and postdormital paralysis occurs when waking up from a deep sleep. It’s a signal that the body and brain are not moving correctly and cooperatively through the stages of sleep.
During non-REM sleep, a person’s body is capable of tossing, turning, talking, and sleepwalking. Once the brain enters REM sleep, however, it inhibits muscular contractions, effectively holding the body rigid, although eyes can still flicker back and forth. It’s during REM sleep that dreams occur, and some sleep specialists believe that REM paralysis helps to prevent people from acting out their dreams, which could be harmful. The nervous system and the endocrine system work together to control the muscles, and sometimes they continue to keep the body on lockdown even as the brain wakes up, causing the sleeper to be conscious, but unable to move. Studies show that incidences of sleep paralysis tend to occur when a person is transitioning from one sleep state to another, and especially if a person is unexpectedly roused from REM sleep.
Being powerless to move is one hallmark of sleep paralysis, but hallucinations and disturbing dreams often accompany the condition. About two thirds of sleep paralysis sufferers report hallucinating during their episodes. Researchers suggest that during REM sleep, the brain not only keeps muscles from moving, it also sends signals to stimulate dreaming. The result is that when a person wakes up into sleep paralysis, the brain is still sending signals to stimulate dreaming, leading to a half-awake dream state. Typical paralysis dreams include the physical sensations of being crushed or inhibited breathing, as well as sensations of flying or floating. The most common hallucination, by far, is the uneasy feeling that an evil presence or intruder is nearby, and fear and anxiety cause many people to try to cry out or call for help, leading to even more fear and anxiety when they realize that they are immobilized.
Sleep It Off
It’s not exactly clear why some people suffer from this confusing condition, although evidence suggests that it’s related to both stress and sleep deprivation. Stress and sleep-related conditions such as PTSD, jetlag, fatigue, changes in routine, narcolepsy, and anxiety can disrupt sleep cycles, making it more likely that the brain will blur the line between REM and non-REM sleep. There’s also a strong correlation between sleep paralysis, panic attacks, and panic disorder. Most people with sleep paralysis report that episodes generally start in the late teens, and that the frequency usually declines by age thirty (although some people experience the paralysis their entire lives). Sleep researchers do know that most sleep paralysis occurs while the sleeper is laying on his back—about 60 percent. There’s also evidence that sleep paralysis increases during the second and third trimesters of pregnancy.
Fortunately, sleep paralysis isn’t harmful, painful, or serious. The worst effects are psychological, since it can be extremely frightening for first-time sufferers or those who already suffer from general anxiety. It’s not a symptom of any serious disease or mental illness, and it generally only lasts from a few seconds to a few minutes, often ending when the sleeper hears a loud noise or feels a touch. For people who experience sleep paralysis frequently, however, it can be distressing and discomforting.
The cure for sleep paralysis is, ironically, more sleep. Maintaining a healthier sleep routine is the key to lessening the likelihood of an occurrence. Frequent sufferers are advised to get plenty of sleep on a regular schedule, and not to eat heavy meals or drink alcohol before bed, both of which can cause sleep disturbances and bad dreams. It’s also important to exercise frequently and reduce stress, try not to sleep on your back, and avoid using drugs.
Doctors can help if sleep paralysis becomes distressing or creates excess anxiety. Antidepressants such as selective serotonin reuptake inhibitors (SSRIs) can help regulate sleep cycles and make symptoms go away. Sometimes treating an existing sleep disorder like restless leg syndrome is enough to eliminate sleep paralysis.
It may be frightening, but at least it’s fleeting. Adjusting sleep schedules can regulate the mixed-up impulses that cause sleep paralysis, making getting a full eight hours’ worth a much more pleasant experience—not a waking nightmare.