The parasomnia not otherwise specified category is for disturbances that are characterized by abnormal behavioral or physiological events during sleep or sleep-wake transitions, but that do not meet criteria for a more specific parasomnia. Examples include

1. REM sleep behavior disorder: motor activity, often of a violent nature, that arises during rapid eye movement (REM) sleep. Unlike sleepwalking, these episodes tend to occur later in the night and are associated with vivid dream recall.
2. Sleep paralysis: an inability to perform voluntary movement during the transition between wakefulness and sleep. The episodes may occur at sleep onset (hypnagogic) or with awakening (hypnopompic). The episodes are usually associated with extreme anxiety and, in some cases, fear of impending death. Sleep paralysis occurs commonly as an ancillary symptom of narcolepsy and, in such cases, should not be coded separately.
3. Situations in which the clinician has concluded that a parasomnia is present but is unable to determine whether it is primary, due to a general medical condition, or substance induced.