<unk>  is characterized by the dreamer acting out their dreams, with complex<unk> s. These dreams often involve screaming, shouting, laughing, crying, arm flailing, kicking, punching, choking, and jumping out of bed. The actions in an episode can result in injuries to oneself or one's bedmate. The sleeping person may be unaware of these<unk> s. Dreams often involve violent or aggressive actions, and an attack theme like being chased by people or animals. Because violence in dreams is more likely to be recalled, this could be an artifact of recall bias or selection bias. The individual with<unk>  may not be aware of having it. In a normal sleep cycle, REM sleep may be experienced at intervals of between 90 minutes and two hours every night, which means<unk>  episodes may occur up to four times a night. Episodes occur more towards the morning hours because that is when REM sleep is more frequent. When awakened, people may be able to recall the dream they were having, which will match the actions they were performing. As the first indication of an underlying neurodegenerative disorder, symptoms of<unk>  may begin years or decades before the onset of another condition. Almost half of those with Parkinson's, at least 88% of those with multiple system atrophy, and about 80% of people with Lewy body dementia have<unk> .<unk>  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<unk>  are found to have a synucleinopathy. Symptomatic<unk>  can also be associated with narcolepsy, Guillain Barre syndrome, limbic encephalitis, and Morvan's syndrome. Other symptoms found in patients with<unk>  are reduced motor abilities, posture and gait changes, mild cognitive impairment, alterations in the sense of smell, impairments in color vision, autonomic dysfunction (orthostatic hypotension, constipation, urinary problems and sexual dysfunction), and depression.
Rapid eye movement sleep behavior disorder
Circadian rhythm sleep disorder
Delayed sleep phase disorder
Advanced sleep phase disorder
Shift work sleep disorder
Idiopathic hypersomnia
Nightmare disorder
Attention deficit hyperactivity disorder