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What is REM sleep behavior disorder?

REM sleep behavior disorder

Rapid eye movement (REM) behavior disorder is a condition that is associated with affected individuals experiencing vivid, and often frightening, dreams as well as performing certain motor behaviors and making vocal noises during the REM phase of sleep. REM sleep makes up about 20 percent of the total sleeping cycle, occurring at the second half of the night, and it occurs many times during sleep time.1

The dreams often have an attacking or chasing element to them, and this causes the individual to perform motor behaviors such as flailing of the arms and legs. The patient will therefore be acting out the movements and sounds according to what they are dreaming.

The cause of REM sleep behavior disorder

Dreaming occurs during REM sleep, and the brain causes temporary muscle paralysis to prevent people from acting out in their dreams and possibly hurting themselves. This occurs because the nerve pathways in the brain are active during REM sleep, which results in the temporary muscle paralysis.2

In REM sleep behavior disorder, the nerve pathways are damaged or don’t work properly and this results in the muscles of the body not being temporarily paralysed, which leads to the mentioned symptoms of the condition.

Risk factors for developing the condition

Certain people are at risk for developing REM sleep behavior disorder. These risk factors include being a male over the age of 50 years, being diagnosed with narcolepsy (which is a chronic sleep condition associated with increased daytime drowsiness), using certain medications such as the newer antidepressants, using illegal drugs and alcohol, and being diagnosed with a neurodegenerative condition.3

This latter group of conditions is defined as those that result in neurological signs and symptoms due to damage to the nerve cells of the brain. These conditions include a stroke (decreased oxygen to the brain), Parkinson’s disease and Lewy body dementia.2 These last two are progressively worsening conditions that affect the brain.  

The clinical picture of REM sleep behavior disorder

 The onset of the symptoms associated with REM sleep behavior disorder can be sudden or gradual, and the episodes may occur occasionally or numerous times a night. As more damage to the nerve cells in the brain occur, so does the worsening of the condition.

The symptoms of REM sleep behavior disorder may include the following:

  • Motor movements that include arm flailing, punching, kicking or jumping or falling from the bed.
  • Vocal noises such as talking, shouting, laughing, crying and even swearing.
  • Once awake, affected individuals are able to clearly recall the dream they just had.4

How the diagnosis is made

REM sleep behavior disorder may be suspected by healthcare professionals purely on the history given by the patient. There are other sleep-related conditions that can mimic the symptoms of REM sleep behavior disorder, or the condition may coexist with other sleep disorders such as narcolepsy or sleep apnea (where patients wake up due to not being able to breathe properly). Therefore, certain special investigations need to be performed to rule out the other possibilities and confirm the diagnosis in order to manage the condition appropriately.

The history given by the patient’s sleeping partner is very important when making the diagnosis of any sleep disorder, because they will be the ones who will notice the exact movements and behaviors of the patient. This is extremely helpful in being able to differentiate between the numerous sleep-related problems.

A polysomnogram (sleep study) is usually performed in such situations. Here, suspected patients are kept overnight in a sleep lab where their heart and breathing rates, brain activity, and blood oxygen saturation levels are monitored. Healthcare professionals also monitor any motor movements or sounds made by the patient. These investigations will also be recorded to closely investigate any possible missed clues.

According to the third edition of International Classification of Sleep Disorders, the following criteria need to be met to confirm the diagnosis of REM sleep behavior disorder:

  • There is a repeated amount of arousal times during sleep where the patient performs complex motor movements or makes noises, and these actions relate to the dream experienced.
  • Patients that awake from these dreams are alert and not disorientated or confused.
  • The patient can clearly recall the dream they had.
  • A polysomnogram shows that the affected person has increased muscle activity during the REM phase of sleep.
  • The sleep disturbance is not caused by any other medication, sleep-related disorder, mental health condition, or substance abuse.5

Complications of the condition

REM sleep behavior disorder may be distressing to the patient’s sleeping partner and even others in the house. Affected patients may even become socially isolated due to fears that others might find out about this sleep-related issue.

The biggest problem though with REM sleep behavior disorder is that patients may end up injuring themselves or others.


The management of REM sleep behavior disorder includes protecting the patient and others from injury, and medications to help aid the patient sleep better.

Protective measures include removing any objects that can be broken or that can hurt the patient when they move around, placing a barrier on the side of the bed to prevent a fall, otherwise padding the floor in case they do fall from the bed, protecting windows from being broken, or even considering a separate bed or room for the patient until the symptoms are controlled.

Medications that can be used to manage the condition include the supplement melatonin, which is a natural hormone produced by the brain.6 It is a well tolerated and effective product with minimal side-effects. If melatonin isn’t effective, then the anti-anxiety medication clonazepam can be used. Side effects of this drug include loss of balance and increased day-time drowsiness, so it should be used with caution and under the supervision of the prescribing physician.


  1. Gagnon, J. F., Bédard, M. A., Fantini, M. L., Petit, D., Panisset, M., Rompre, S., ... & Montplaisir, J. (2002). REM sleep behavior disorder and REM sleep without atonia in Parkinson’s disease. Neurology59(4), 585-589.
  2. Boeve, B. F., Silber, M. H., Saper, C. B., Ferman, T. J., Dickson, D. W., Parisi, J. E., ... & Tippman-Peikert, M. (2007). Pathophysiology of REM sleep behaviour disorder and relevance to neurodegenerative disease. Brain130(11), 2770-2788.
  3. Postuma, R. B., Iranzo, A., Hogl, B., Arnulf, I., Ferini‐Strambi, L., Manni, R., ... & Puligheddu, M. (2015). Risk factors for neurodegeneration in idiopathic rapid eye movement sleep behavior disorder: a multicenter study. Annals of neurology77(5), 830-839.
  4. Olson, E. J., Boeve, B. F., & Silber, M. H. (2000). Rapid eye movement sleep behaviour disorder: demographic, clinical and laboratory findings in 93 cases. Brain123(2), 331-339.
  5. Zucconi, M. A. R. C. O., & Ferri, R. A. F. F. A. E. L. E. (2014). Assessment of sleep disorders and diagnostic procedures. ESRS European sleep medicine textbook. Regensburg: European Sleep Research Society, 96.
  6. Boeve, B. F., Silber, M. H., & Ferman, T. J. (2003). Melatonin for treatment of REM sleep behavior disorder in neurologic disorders: results in 14 patients. Sleep medicine4(4), 281-284.