REM sleep parasomnias and degenerative diseases of the central nervous system

: Parasomnias are defined as unpleasant and undesirable behavioral (in the sense of action) or experiential (in the sense of sensorial or perceptive) phenomena which overwhelmingly or exclusively happen during sleep. Former attitudes that parasomnias are closely related to psychiatric derangement are abandoned and newer polysomnographic research indicates that we are dealing with a number of totally different organically defined states, most of which are easy to diagnose and even cure. The frequency of parasomnias in population is much higher than so far supposed so that they are considered among the most frequent disturbance of the CNS. Another inglorious record tightly connected to parasomnias is that they belong to the most frequently undiagnosed or misdiagnosed diseases. Clinically the most important and intriguing of the parasomnias associated with REM sleep, is REM sleep behavior disorder (RBD). In the last few decades in the field of human and animal sleep, researchers have noticed that RBD represents the omen of the more complex degenerative disorders of the central nervous system--the synucleinopathies and tauopathies. RBD can precede these disorders for decades before the florid clinical picture becomes obvious.