Recognize parasomnias within the sleep cycle

A parasomnia is an undesirable physical or experiential event that accompanies sleep. They can appear as movements, emotions, perceptions, and dreams. Changes in the autonomic nervous system with skeletal muscle activity are hallmarks of a parasomnia, and it is not uncommon for a patient to experience more than 1 parasomnia.

Identifying a parasomnia is easier when you can tell when it occurs while you sleep. Parasomnias that occur during non-REM sleep include excitement of confusion, sleepwalking, and sleep terrors. Those that occur during REM sleep include REM sleep behavior disorders, recurrent isolated sleep paralysis, and nightmare disorders.

Parasomnias that occur during non-REM sleep, such as sleepwalking and terrors, are commonly seen in children. Wake up a child from this phase of sleep and you will likely see confusing excitement too. Patients are disoriented and can speak slowly. They are also unlikely to remember being woken up and easily falling asleep again.

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Parasomnias that occur during REM sleep are commonly seen in the elderly. Patients with REM sleep behavior disorder are more likely to be over 60 years old. Sleep paralysis can occur at any age, but it usually occurs in young adults. Nightmares can also be seen at any age, but terrors tend to happen to those who are a little older.

Parasomnias that occur during non-REM sleep are more in the early stages of sleep. For example, sleepwalking occurs during the first half of the sleep period. Patients can exhibit very sophisticated behaviors and may not remember anything that happened during the event. Sleep speech, on the other hand, can occur in non-REM and REM sleep.

Parasomnias that appear later in the are often associated with REM sleep. REM sleep occurs roughly every 90 minutes, but each REM phase grows longer as the progresses. The final REM stage can last for a long time, making the chance of REM sleep parasomnia more likely later in the night.

When assessing what parasomnia a patient may have experienced, the first thing to do is determine when it occurred during the night and this can help you with your diagnosis. Some are easier to pinpoint than others. Diagnosing sleepwalking is fairly easy, but pinpointing a nightmare or sleep scare can be more of a challenge.

I will be writing more about these interesting parasomnias in the coming weeks! Stay tuned.

Sharon M. O’Brien, MPAS, PA-C, is a practicing physician assistant and health coach in Asheville, NC.


  1. Kryger MH, Roth T, Dement WC. Principles and Practice of Sleep Medicine. 4th ed. Elsevier Health Sciences. 2005.

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