Dyssomnias, parasomnias, and sleep disorders associated with medical and psychiatric diseases.

Sleep disorders can be intrinsic, as are insomnia or narcolepsy, or can be accounted for by external factors, such as noise, altitude, drug or alcohol abuse, or shift work. The arousal disorders, common in children, are usually benign and disappear by puberty. Sleep-wake transition disorders such as sleep starts are benign as well, and may occur at any age. The parasomnias comprise different entities such as nightmares, REM-sleep behavior disorder, sleep enuresis, and bruxism. Diagnosis and treatment often require a multidisciplinary approach. Virtually every psychiatric, neurologic, or medical disease, when of sufficient severity, leaves its specific fingerprint on sleep; some disorders, such as peptic ulcer disease, gastroesophageal reflux, or epilepsy, tend to be exacerbated during sleep. Fortunately, most sleep disorders are amenable to therapy, which can include counseling, sleep hygiene, withholding of an offending agent, behavioral therapy, light therapy, or cautious drug therapy.