Things that go bump in the night: the parasomnias revisited.

The parasomnias have been identified as a major category of sleep disorders and represent a group of physiologic and behavioral phenomena that occur exclusively during, or are augmented by, the sleeping state. They are commonly encountered in clinical practice and are typically dismissed as "bumps in the night" or attributed to psychiatric disease. Despite their often bizarre nature, most are readily explainable, diagnosable, and treatable. Some have formed the basis for art, literature, and folklore. Pertinent references from a wide variety of disciplines have been collected, and a clinical classification of the parasomnias is proposed to assist in the understanding, diagnosis, and management of these fascinating disorders.