Spectrum of rapid eye movement sleep behavior disorder (overlap between rapid eye movement sleep behavior disorder and other parasomnias)

Parasomnia Overlap Disorder (POD) was described and named in 1997 with a series of 33 cases of rapid eye movement (REM) sleep behavior disorder (RBD) combined with a disorder of arousal from non-rapid eye movement (NREM) sleep (sleepwalking, sleep terrors) that emerged idiopathically or symptomatically with neurological and other disorders. POD is a subtype of RBD in the International Classification of Sleep Disorders Diagnostic and Coding Manual, second edition (ICSD-2). An updated classification of POD also includes subclinical RBD-NREM parasomnia, RBD-sleep-related eating disorder, RBD-sexsomnia, RBD-rhythmic movement disorder, and status dissociatus (SD), which is another subtype of RBD in the ICSD-2. Similar to POD, a core feature of SD is sleep motor-behavioral dyscontrol, with release of dream-related behaviors suggestive of RBD, but with nearly continuous ambiguous polygraphic sleep precluding the identification of NREM/REM sleep states. SD exemplifies extreme state dissociation. SD is always a symptomatic disorder, and is causally associated with a broad range of neurologic disorders, often with thalamic, limbic, striatal, and pontine involvement. The parasomnia behaviors associated with POD and SD - typical RBD behaviors - can often be controlled with bedtime clonazepam therapy, including the abnormal dreaming.