The parasomnias: epidemiology, clinical features, and diagnostic approach.

Parasomnias are a group of disorders exclusive to sleep and wake-to-sleep transition that encompass arousals with abnormal motor, behavioral, or sensory experiences. Sensory experiences often involve but are not limited to perceptions, dreamlike hallucinatory experiences, and autonomic symptoms. When accompanied with excessive motoric activity and other complex motor behaviors, these parasomnnias can be disruptive to the patient and bed partners. Motor behaviors may or may not be restricted to bed but can become dangerous when the subject ambulates or is agitated. The behaviors are inappropriate for the time of occurrence but may seem purposeful or goal directed. Most parasomnias are more common in children and decrease in frequency as they get older. Parasomnias have been reported in approximately 4% of the adult population.