Rapid Eye Movement (REM) Sleep Behaviour Disorder

What is REM sleep?

Sleep is split up into different “stages” through the night. Rapid Eye Movement (REM) sleep is a stage which first occurs around 90 minutes after you fall asleep. The first period of REM normally lasts around 10 minutes, and as sleep continues there tends to be more REM in the second half of the night.

It is called ‘rapid eye movement’ sleep because your eyes will move more rapidly behind closed eyelids.

During REM, dreams may be much more vivid. This is due to the fact that the brain is more active during this stage.

REM sleep is important and is associated with many aspects of health and brain function. Therefore it is important to get enough REM sleep to be better able to function during the day.

The image below shows the stages of sleep we move through in a typical night. Non REM stage 1 is light sleep and Non REM stage 3 is deep sleep.

What are parasomnias?

Parasomnia is a word used to describe unusual behaviours that occur during sleep. There are many different forms, with sleepwalking being the classic example. Sleepwalking and sleep terrors are Non REM parasomnias (occurring from Non REM Stage 3 - “deep sleep”). They are common during childhood but occur more rarely in adults.

When abnormal events occur during REM sleep, then they are known as REM parasomnias.

REM-related parasomnias include:

REM sleep behaviour disorder

People begin “acting out their dreams” by vocalizing or moving their arms and legs during REM sleep. They may recall dream content associated with the behaviour if they wake up - such as calling for help, trying to hit something or trying to defend themselves.

It is caused by a failure of the normal mechanism which keeps people still during dreams. It can cause poor sleep quality and unintended injuries to yourself or your partner.

Recurrent isolated sleep paralysis

People with this condition wake up but are unable to speak or move their body at all for several seconds. Around half of people will experience this once, but frequent episodes can cause anxious feelings about going to sleep.

Nightmare disorder

This condition describes those who have recurrent, vivid dreams, usually about threats to survival or safety. It may lead to poor sleep quality, fatigue, distress even during the day, and other psychological symptoms.

Non-REM and REM parasomnias

Non-REM parasomnias REM parasomnias
Sleeping walking REM sleep behaviour disorder
Sleep terrors Recurrent isolated sleep paralysis
Confusional arousals Nightmare disorder
Sleep-related eating disorder  
Abnormal sexual behaviours during sleep  

Why is this happening to me?

REM sleep disorders are usually caused by a problem with the part of the brain that sends information down the spine to the muscles. During normal REM sleep, these cells keep your muscles still so you don’t act on your dreams. However, with this problem, it means the body is able to act out behaviours associated with dreams during the night.

There are some risk factors which may make someone more likely to develop a REM parasomnia, and these include:

  • Being male
  • Being aged over 50
  • Having other neurological disorders such as Parkinson’s Disease
  • Having other sleep disorders such as narcolepsy
  • Taking certain medications such as antidepressants, or the use or withdrawal of alcohol and/or other illicit drugs
  • Having post traumatic stress disorder

There may be no particular reason in which people develop these sleep disorders. However, in a lot of cases, people subsequently go on to develop certain types of neurodegenerative disorders such as Parkinson’s and Lewy body dementia. This may be several decades later. REM sleep disorders can sometimes be the first symptoms that present in these conditions. This is why it is important that you discuss any symptoms or concerns that you may have with your doctor.

How are REM parasomnias diagnosed?

Person lying in a bed with sleep testing equipment attached to his head and face.

A detailed sleep history is sometimes enough on its own to make a diagnosis of an REM sleep behaviour disorder, especially if there is already a diagnosis of an associated condition such as Parkinson’s Disease.

A one or two night inpatient sleep study may be needed. This is known as “Polysomnography” (which means taking multiple measurements during sleep).

Polysomnography involves the use of a number of wires which are stuck to the patient, which are used to take various measurements of the body during sleep. The important thing we look for in REM behaviour disorder is muscle tension during REM sleep. 

Image credit: File:Polysomnography model.jpg - Wikimedia Commons

How are REM parasomnias treated?

Management of REM sleep behaviour disorder includes providing physical safeguards in your sleep environments, and some medications which may be offered to help with the condition.

Physical safeguards

Some examples of adjustments that may be suggested to keep you and your bed partner safe include:

  • Padding near the bed
  • Soft barriers at the side of the bed
  • Moving clutter and sharp-edged furniture away from the bed
  • Some partners put a large pillow between them during the night

Other factors

Stress and poor quality sleep can make REM sleep behaviour
disorder worse.

Sleep hygiene is a term used to describe a healthy approach to the management of sleep and wakefulness. This can often improve not just the quality of sleep but also help with sleep disorder symptoms. Examples of sleep hygiene measures are listed below.

Sleep hygiene measures

  • Regular waking times and bedtimes
  • Avoid caffeine in the afternoon and keeping the amount low in the morning
  • Avoiding stimulating activity in the hours before bed
  • Psychological relaxation techniques prior to sleep
  • A comfortable, quiet sleeping environment at the right temperature
  • Trying to sleep enough so as not to need an alarm clock to wake in the morning
  • Avoiding alcohol or other sedatives before sleep


Medication is not always needed, but may be used if the condition is severe, distressing or causing injuries. The most common medications that may be offered are:


This acts as a sedative in order to help reduce arousal during the night. However there may be side effects such as daytime tiredness, impaired balance and slower breathing during the night.


This is a hormone that exists naturally in the brain, which can be supplemented. It can help reduce the severity and frequency of REM parasomnia. It has fewer side effects than clonazepam.

Stopping other medications

Some medications can cause or worsen REM sleep behaviours, and should be discussed at your initial appointment. Some examples of medications that might be having an effect include:

  • Antidepressants
  • Beta blockers
  • Alzheimer’s medications

Where to find more information

If you are seeking any further information that was not covered on this page, here are some free resources.

American Academy of Sleep Medicine


The Sleep Foundation


How to contact us

Rosa Burden Centre

Southmead Hospital



BS10 5NB

Telephone: 0117 414 0450

If you or the individual you are caring for need support reading this information please ask a member of staff for advice.

If you’re an overseas visitor, you may need to pay for your treatment or you could face fraud or bribery charges, so please contact the overseas office: Tel: 0117 414 3764 Email: overseas.patients@nbt.nhs.uk

Rapid Eye Movement (REM) Sleep Behaviour Disorder