|Rapid eye movement behavior disorder|
|Classification and external resources|
Rapid eye movement sleep behavior disorder (RBD) is a sleep disorder (more specifically a parasomnia) that involves abnormal behavior during the sleep phase with rapid eye movement (REM sleep). It was first described in 1986.
The major and arguably only abnormal feature of RBD is loss of muscle atonia (paralysis) during otherwise intact REM sleep. This is the stage of sleep in which most vivid dreaming occurs. The loss of motor inhibition leads to a wide spectrum of behavioral release during sleep. This extends from simple limb twitches to more complex integrated movement, in which sufferers appear to be unconsciously acting out their dreams. These behaviors can be violent in nature and in some cases will result in injury to either the patient or their bed partner.
RBD is characterized by the dreamer acting out his or her dreams. Usually negative ones which involve kicking, screaming, punching, grabbing, and even jumping out of bed. When awakened, one can usually recall the dream they were having which will match the actions they were performing, but they will not be aware that they were moving. Episodes occur more towards the morning hours because that is when REM sleep is more frequent. People with RBD experience episodes at least once a week, sometimes more and each episode can result in injuries to oneself or one's bed partner.
Rapid eye movement behavior disorder occurs when there is a loss of normal voluntary muscle atonia during REM sleep resulting in motor behavior in response to dream content. It can be caused by adverse reactions to certain drugs or else during drug withdrawal; however it is most often associated with the elderly and in those with neurodegenerative disorders such as Parkinson disease, and other neurodegenerative diseases for example multiple system atrophy and lewy Body Dementia.
RBD is treatable. Various medications are prescribed for RBD based on varying symptoms. Low doses of clonazepam is most effective with a 90% success rate, how this drug works to restore REM atonia is unclear, however it is thought to suppress muscle activity, rather than directly restoring atonia. Melatonin is also effective and can also be prescribed as a more natural alternative. For those with Parkinson's and RBD, Levodopa is a popular choice. In addition to medication it is also wise to secure the sleeper's environment in preparation for episodes. Remove potentially dangerous objects from the bedroom and either place a cushion around the bed or move the mattress to the floor for added protect against injuries. Pramipexole is another drug which can be an effective treatment option.
The most comprehensive assessment so far has estimated RBD prevalence to be around 0.5% in individuals aged 15 to 100. It is far more common in males: most studies report that only around a tenth of sufferers are female. This may partially be due to a referral bias, as violent activity carried out by men is more likely to result in harm and injury and is more likely to be reported than injury to male bed partners by women, or it may reflect a true difference in prevalence as a result of genetic or androgenic factors. The mean age of onset is estimated to be around 60 years.
Various conditions are very similar to RBD in that sufferers exhibit excessive sleep movement and potentially violent behavior. Such disorders include sleepwalking and sleep terrors, which are associated with other stages of sleep, nocturnal seizures and obstructive sleep apnea which can induce arousals from REM sleep associated with complex behaviors. Because of the similarities between the conditions, polysomnography plays an important role in confirming RBD diagnosis.
It is now apparent that RBD appears in association with a variety of different conditions. Narcolepsy has been reported as a related disorder. Both RBD and narcolepsy involve dissociation of sleep states probably arising from a disruption of sleep control mechanisms. RBD has also been reported following cerebrovascular accident and neurinoma (tumour), indicating that damage to the brain stem area may precipitate RBD. RBD is usually chronic, however may be acute and sudden in onset if associated with drug treatment or withdrawal (particularly with alcohol withdrawal) 60% of RBD is idiopathic. This includes RBD that is found in association with conditions such as Parkinson’s disease and dementia with Lewy bodies, where it is often seen to precede the onset of neurodegenerative disease. Monoamine oxidase inhibitors, tricyclic antidepressants, serotonergic synaptic reuptake inhibitors, and noradrenergic antagonists can induce or aggravate RBD symptoms and should be avoided in patients with RBD.