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Parasomnias: Things That Go Bump in the Night

En Español (Spanish Version)

nightmares.gif 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 are 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 a.m., 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 unpleasant or undesirable behavioral or experiential phenomena during sleep.

Defining Parasomnia

Abnormal things that can happen to people while they are sleeping are called parasomnias.

Examples of parasomnias include sleepwalking and night terrors.

While they can be frightening to observe, most parasomnias are harmless 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.

The Difference Between REM and Non-REM Disorders

Parasomnias fall into two main categories—disorders of REM sleep and non-REM (NREM) sleep.

REM, short for rapid eye movement, sleep is the most active stage of sleep during the second half of the night. This is when most dreams and nightmares occur. During REM sleep, our muscles become relaxed and immobile to keep us from acting out our dreams. In those with REM behavior disorder, the muscles do not relax and people act out their dreams as though awake. Some things that may occur during this time are hitting, punching, or yelling. This disorder can lead to injury of the dreamer or the bed partner. During this time, the dreamer is really asleep.

For most of the night, we are in NREM sleep, which includes the deep sleep. This is when sleepwalking and night terrors occur.

A major difference between the nightmares of REM sleep and the night terrors of NREM 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.


Sleepwalking is more prevalent in children than adults. There are many reasons people sleepwalk, but one common theory is that it is hereditary.

During this time, the sleepwalker may be unresponsive and appear awake. Sometimes awakening the sleepwalker can trigger aggression and violent behavior. It is best not to wake the sleepwalker. Try to redirect the person back to bed if possible.

Night Terrors

Night terrors differ from nightmares. They occur during non-REM sleep, generally in the first third of the night. They may include incomplete arousal, confusion, unresponsiveness, and amnesia. They can occur in a small minority of children up to 8 years old. Night terrors may also be accompanied by sleepwalking.

Keep in mind that night terrors may render a child inconsolable for several minutes. Once relaxed, the child will often fall back to sleep.

How Do You Treat Parasomnias?

The good news is that most of these things eventually go away on their own. Some people however, need more involved treatment.

If someone's behavior associated with parasomnias is violent, causing injuries to the patient or others, treatment with a class of medicines called benzodiazepines can be effective. However, most doctors consider medicine a last resort. Other treatments for adults include, psychotherapy and hypnosis. Treatment often accompanies preventive measures that can help at home.

Prevention Tips

Here are some tips for preventing parasomnias:

  • Keep the same sleep schedule and get enough sleep. This will prevent the increase in deep sleep that can trigger sleepwalking, night terrors, and other parasomnias.
  • 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.

Other Safety Measures

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

  • Lower the bed to the floor. It is harder to get up out of a mattress on the floor.
  • Sleep in a sleeping bag. It is harder to get out of than typical blankets.
  • If bedrooms are on the 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 night terror, he won't hurt himself. Do not try to restrain him; it can make him more agitated.

If your child has frequent nightmares, night terrors, or sleepwalks, contact your child's pediatrician for additional advice.


National Center on Sleep Disorders Research


National Sleep Foundation



Better Sleep Council Canada


The Canadian Sleep Society



Nightmares and Sleep. National Sleep Foundation website. Available at: http://www.sleepfoundation.org/article/sleep-related-problems/nightmares-and-sleep. Accessed January 7, 2013.

Night Terrors. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/what.php. Updated August 16, 2012. Accessed January 7, 2013.

Parasomnias. National Heart Blood Lung Institute website. Available at: http://www.sleepfoundation.org/article/ask-the-expert/sleep-and-parasomnias. Accessed January 7, 2013.

Sleepwalking. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/what.php. Updated January 1, 2013. Accessed January 7, 2013.

Sleep and Parasomnias. National Sleep Foundation website. Available at: http://www.sleepfoundation.org/article/ask-the-expert/sleep-and-parasomnias. Accessed January 7, 2013.

What Happens When You Sleep? National Sleep Foundation website. Available at: http://www.sleepfoundation.org/article/how-sleep-works/what-happens-when-you-sleep. Accessed January 7, 2013.

Last reviewed January 2013 by Brian Randall, MD

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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