ABSTRACT
DEFINITION OF PRIMARY INSOMNIA Primary insomnia is a diagnostic category in the psychiatric classification of the Diagnostic and Statistical Manual for Mental Disorders, Fourth Edition [DSM-IV (1)]. It is characterized by (a) difficulty initiating or maintaining sleep or nonrestorative sleep of at least one month duration that (b) causes significant distress or impairment in an important area of functioning and (c) does not occur exclusively in the context of another sleep disorder, or (d) mental disorder, and (e) is not due to the direct physiological effects of a substance. The American Academy of Sleep Medicine Work Group proposed a slightly refined Research Diagnostic Criteria (RDC) for primary insomnia (2). Under the RDC, an “insomnia disorder” that includes the presence of nocturnal symptoms and its associated waking complaints is distinguished from “insomnia symptoms,” which include the nocturnal complaints only. As is true for the DSM-IV diagnosis, the RDC also requires that a primary insomnia disorder does not occur exclusively in the context of another medical, psychiatric or substance abuse disorder, or, if another disorder is present, the course of the insomnia disorder shows some independence from the temporal course of that disorder (2). This minor difference in criteria not withstanding, the diagnostic assessment of primary insomnia requires ascertaining the presence of an insomnia disorder and ruling out comorbidities that might be the primary reason for the reported sleep difficulties.
