Parasomnias include undesirable activities that occur during sleep onset, arousal from sleep or during sleep. Most parasomnias occur during NREM sleep. Hallmark features of this common sleep disorder include abnormal behavior most commonly occurring during deep, slow wave / stage III sleep. Factors that influence sleep and may play a role in parasomnia disorders include: emotional stress, sleep deprivation, medications, alcohol and psychological trauma. Progressive neurologic conditions such as Parkinson’s disease can lead to a parasomnia known as REM Sleep Behavioral Disorder. This sleep disorder is characterized by abnormal aggressive movements during REM sleep.

Studies have shown a possible heredity component in some patients with NREM parasomnias like sleepwalking. Sleepwalking (somnambulism) is linked to NREM sleep instability. This is due to an elevation in the arousal or wake threshold. Parasomnia disorders in adults may also be precipitated by hypnotics, lithium and antihistamine medications. Some parasomnias in children are self-limited and will grow out of it as they approach adolescents. A parasomnia diagnosis is guided by clinical history. An overnight polysomnogram may be necessary to rule out other sleep disorders.