Brainstem circuits that control atonia during REM sleep may be damaged, including those in the pontomedullary brainstem. REM sleep circuits are located in caudal brainstem structures—the same structures that are known to lead to be implicated in the synucleinopathies. Motor deficits like those seen in RBD are known to result from lesions in those circuits.Risk factors for developing RBD are a family history of acting out dreams, prior head injury, farming, exposure to pesticides, low education level, depression, and use of antidepressants.RBD may be acute and sudden in onset if associated with drug treatment or withdrawal (particularly with alcohol withdrawal). Antidepressant medications can induce or aggravate RBD symptoms. Diagnosis
There are two ways to diagnose RBD:  by documenting a history of complex, dream-enactment sleep behaviors, or by polysomnography recording of these behaviors along with REM sleep atonia loss.RBD may be established from clinical interview as well as several validated questionnaires, when sleep studies cannot be performed. Questionnaires such as the Rapid Eye Movement (REM) sleep Behavior Disorder Screening Questionnaire (RBDSQ), the REM Sleep Behavior Questionnaires – Hong-Kong (RBD-HK), the Mayo Sleep Questionnaire (MSQ) and the Innsbruck REM Sleep Behavior Disorder Inventory are well-validated. Individuals with RBD may not be able to provide a history of dream enactment behavior, so bed partners are also consulted.
It is more common in males overall, but equally frequent among men and women below the age of 50. 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. Typical onset is in the 50s or 60s.Almost half of those with Parkinsons, at least 88% of those with multiple system atrophy, and about 80% of people with Lewy body dementia have RBD. RBD is a very strong predictor of progression to a synucleinopathy (for example, the Lewy body dementias). On autopsy, up to 98% of individuals with polysomnography-confirmed RBD are found to have a synucleinopathy. History
In the 1960s and 1970s, Michel Jouvet described brain lesions in cats that led to loss of atonia in REM sleep. Carlos Schenck and Mark Mahowald and their team in Minnesota first described RBD in 1986. In animals
RBD has also been diagnosed in animals; specifically dogs. See also
Sleepwalk with Me
Pseudobulbar affect
Gelastic seizure

References
Further reading
Roguski A, Rayment D, Whone AL, Jones MW, Rolinski M (2020). "A Neurologists Guide to REM Sleep Behavior Disorder". Front Neurol (Review). 11: 610. doi:10.3389/fneur.2020.00610. PMC 7360679. PMID 32733361.