Approach to the patient with a sleep complaint.

There have always been sleep disorders, many of which have been recognized for centuries, and some of our treatments have even been dated from the past. However, there has been a dramatic increase in knowledge about sleep disorders and their treatments in the past 20 years. It is now possible to objectively diagnose most sleep disorders and new, specific treatments can be instituted. The recent recognition of chronobiology has resulted in an understanding of the alterations in the sleep-wake pattern of humans. Genetic causes of sleep disorders, such as advanced sleep phase syndrome, have shed new light on disorders that were previously believed to be largely behaviorally produced. Neurochemical changes have led to a better understanding of the pathophysiology of some disorders such as narcolepsy. However, despite advances in our understanding of sleep disorders, accurate diagnosis and treatment always requires a detailed understanding of the patient's sleep-wake cycle and medical history. The art of good sleep medicine still lies in the ability of the clinician to take a thorough history, develop a differential diagnosis, and formulate a treatment plan. This article details the important elements of the clinical evaluation.