What every clinician should know about polysomnography.

Polysomnography studies are an essential tool for the sleep physician and aid in the diagnosis and treatment of sleep disorders. Polysomnography refers to the recording, analysis, and interpretation of multiple physiologic signals collected simultaneously. Rapid advancements in technology have transformed the field from a time when analog studies were collected on paper to computer-assisted collection of digitally transformed studies. Sleep clinicians, whether physicians, respiratory therapists, or sleep technologists, must therefore have an understanding of a broad array of principles underlying the collection of the various signals. In addition, an understanding of basic technical rules in the evaluation of polysomnography studies is necessary for both the scoring and interpretation of such studies. The American Academy of Sleep Medicine published a new manual for the scoring of sleep and associated events in 2007. These changes included modifications to the visual scoring of sleep, the scoring of sleep-disordered breathing events, and movement disorders during sleep. A few early studies have evaluated the effects of the changes in scoring guidelines to the previous Rechtschaffen and Kales (R&K) rules for sleep and the American Academy of Sleep Medicine rules for respiratory events. Some controversy regarding the scoring of respiratory events continues to exist and requires further studies to be performed.