Parasomnias: Things That Go Bump in the Night
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Parasomnias: Things That Go Bump in the Night


A mother is awakened in the middle of the night by a terrifying scream. She races to the room of her three-year-old son, who is sitting up in bed with tears running down his face, his heart pounding. The more she tries to soothe him, the more agitated he becomes.

A college student walks into her parents' bedroom while they're sleeping and pours a glass of water into her mother's dresser drawer.

A physician takes a telephone call from the emergency room at 3 am, receives information about a complex case, and then gives completely inappropriate instructions for the patient's care.

What all these people have in common is that, in the morning, none of them remembers a thing.

These stories—all true—are examples of parasomnias, which are defined as "unusual behavioral or experiential phenomenon during sleep."

What Is a Parasomnia?

"Anything that goes bump in the night is parasomnia," says Dr. Mark Mahowald, a neurologist at the Minnesota Regional Sleep Disorder Center and a leading researcher in this field of sleep disorders.

Parasomnias include sleepwalking, talking during sleep, and sleep terrors. Bed-wetting, when there's not an underlying urologic condition, also is considered a parasomnia. Some medical literature also include grinding the teeth, called "bruxism," and rhythmic movement disorders, such as head-banging or rocking and rolling, which is almost always limited to infants.

While they can be frightening to observe, most parasomnias are benign and require no treatment beyond some simple safety measures to keep people from injuring themselves during an episode.

Parasomnias are more common in children than in adults because the condition most often occurs during deep sleep, which decreases as we age. "Our sleep matures," says Dr. Dainis Irbe, a neurologist the Emory Children's Center in Atlanta, and director of the Sleep Laboratory at Children's Healthcare of Atlanta at Egleston. "Kids reach stages of adult sleep by age six, roughly."

REM vs. Non-REM Disorders

Parasomnias fall into two main categories—REM sleep and non-REM sleep disorders.

REM, short for "rapid eye movement," sleep is the lighter stage of sleep that we have during the second and third phases of the night. This is when most dreams and nightmares occur.

Because we spend more time in REM sleep, there is "more opportunity to get those symptoms, usually associated with waking up after a bad dream," says Dr. Irbe. "[The person] might scream, look around, be confused. You can communicate with him, he'll respond, he'll remember what he dreamt about, and can tell you in detail."

Normally, REM sleep is accompanied by active muscle paralysis, which is the body's way of protecting itself (and others) during dreams. "Our brains are going into high gear during REM sleep," Dr. Mahowald explains. "[Without the paralysis] we could act on brain activity." People with REM sleep behavior disorder, who are almost always older men, lack that paralysis and act physically on their dreams. "A good example is the man who thinks he's playing football and thinks he's making a catch and injures himself falling on the floor," says Dr. Mahowald.

Non-REM sleep is the deep rest that normally occurs during the first phase of sleep. That's when sleepwalking, sleep talking, and confusional arousals, such as sleep terrors, occur.


Sleepwalking, Dr. Mahowald says, is "part of the human condition. Almost every parent of a young child has found the child sleeping somewhere he's not supposed to be." About 10% of adults walk in their sleep, and there's evidence that it can be hereditary.

There's some wisdom to the folk advice not to wake a sleepwalker, or a person with night terrors, for that matter. Dr. Rachel Zak from the NewYork-Presbyterian Hospital Sleep Wake Disorders Center explains that during these times, people aren't rational and could lash out. "You don't know what to expect," she says. "It's not necessarily that they will cause violence, [but] they're just not fully conscious. What you try to do is help them back to bed." Plus, make sure windows are latched and doors are locked. A gate across stairs could be helpful, too.

Sleep Terrors

Sleep terrors, which can occur at night or during daytime naps, are the most extreme form of arousal disorders. According to Dr. Mahowald, a person may sit or jump up and there is often, what family members describe as, a blood-curdling scream. The person may even be running around or throwing things. He appears to be awake, but clearly is not awake and is very difficult to arouse. He may be breathing very rapidly, have prominent sweating, and look absolutely terrified. "Yet if [he's] not awakened during the episode, [he's] totally unaware in the morning. That's generally true for sleepwalking too. There's almost total amnesia," says Dr. Mahowald.

Another major difference between the nightmares of REM sleep and the sleep terrors of deep sleep is that nightmares involve a complex plot that can be recalled in detail, while the images involved with night terrors are very primitive and simplistic, such as fire, a monster, or the ceiling falling in.


Bed-wetting, also called enuresis, in people up to age five is not a major concern, Dr. Irbe says. But after that, it's considered a problem, since fewer than 5% of those cases are related to a urinary tract problem. "It could be because of training problems or it could be family problems," he says. "Also, many times, enuresis is associated with underlying sleep deprivation, restless sleep, sleep fragmentation, and sleep apnea."

Generally, children grow out of parasomnias, and they require no treatment beyond a physician reassuring their parents that the condition is not serious.


If someone's behavior associated with parasomnias are violent, causing injuries to the patient or others, treatment with a class of medications called benzodiazepines can be very effective. However, most physicans consider medication a last resort. "The question is, do you want to give a medicine every single night that we know affects the brain?" Dr. Zak says. "We don't know what effects it has. We don't want to give a child a psychoactive drug every night for something that occurs rarely. Part of [the decision] is how frequently it occurs."

Dr. Mahowald teaches patients to use hypnosis or self-relaxation techniques before they go to sleep. "It appears the arousal still happens, but not the behaviors," he says. "It's quite effective in children and adults, and that's the treatment we'd prefer."


Here are some tips for preventing parasomnias:

  • Keep the same sleep schedule and avoid sleep deprivation. That will prevent the need for deep sleep that can trigger sleepwalking, sleep terrors, and other parasomnias.
  • Avoid mind-stimulating activities before bed, such as action movies, TV shows, or computer games.
  • Engage in calming activities, such as listening to soothing music, talking, or reading, and don't have a TV in your bedroom.
  • Avoid big meals close to bedtime; late digestion disrupts your continuity of sleep. Caffeine causes sleep fragmentation, and one study suggests that drinking any kind of liquid before bedtime can trigger sleep terrors.
  • Parents can keep a diary for a week or two of a child's parasomnias, which will usually occur about the same time. Once that time is established, wake the child up about 30 minutes before an event, just enough so the child opens his eyes and recognizes you. Then let him go back to sleep.


There are some general safety precautions you can take if you or someone you know experiences parasomnias:

  • Make the bed lower to the floor and pad it with pillows.
  • If bedrooms are on a second floor, move the bed to the first floor.
  • Latch windows and lock doors.
  • Put gates across stairwells.
  • Put bells or alarms on door knobs.
  • If a person is staying in bed during a sleep terror, he won't hurt himself. Don't try to restrain him; it can make him more agitated.


American Academy of Sleep Medicine

National Center on Sleep Disorders Research

National Sleep Foundation

Last reviewed August 2007 by J. Thomas Megerian, MD, PhD, FAAP

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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