In many cases, a disturbance of sleep is one of the symptoms of another disorder, either mental or physical. Whether a sleep disorder in a given patient is an independent condition or simply one of the features of another disorder classified elsewhere, either in this chapter or in others, should be determined on the basis of its clinical presentation and course as well as on the therapeutic considerations and priorities at the time of the consultation. Generally, if the sleep disorder is one of the major complaints and is perceived as a condition in itself, the present code should be used along with other pertinent diagnoses describing the psychopathology and pathophysiology involved in a given case. This category includes only those sleep disorders in which emotional causes are considered to be a primary factor, and which are not due to identifiable physical disorders classified elsewhere.