Sleep Disorders: Classification and Diagnosis

This chapter reviews classification schemes of sleep disorders and discusses assessment procedures commonly used to derive a diagnosis. Three different classifications, based predominantly on expert opinions and consensus, have evolved in parallel over the last few decades. Two of them are incorporated within larger taxonomies, such as the International Classification of Diseases (ICD) from the World Health Organization and the Diagnostic and Statistical Manual of Mental Disorders (DSM) from the American Psychiatric Association. A more specialized taxonomy, the International Classification of Sleep Disorders, has been developed by sleep medicine and research societies. Historically significant discrepancies have existed among these classification systems. However, increased collaboration among the nosologists charged with the development and refinement of these systems has made significant advances in increasing the concordance of these distinctive taxonomies. Yet the validity and reliability of the disorders listed in these classification schemes remain uneven, with some disorders supported by extensive empirical evidence and ascertained via reliable objective assays and others based primarily on consensus and identified largely by the questionably reliable clinical interview. Despite somewhat uneven evidence supporting the validity and reliability for the disorders these systems describe, they remain widely used by clinicians and researchers. Regardless of the system in use, accurate diagnosis is based on a multilevel assessment including a clinical interview, screening questionnaires and self-monitoring and in some cases laboratory procedures, and ambulatory behavioral assessment devices. Further research is needed to examine the validity and reliability of various sleep disorders and the clinical utility of current taxonomies.