Classification of Sleep Disorders

In the revised International Classification of Sleep Disorders Diagnostic and Coding Manual (ICSD-DCM), the American Sleep Disorders Association (ASDA; 1990) broadly classifies three categories of disordered sleep: 1) dyssomnias, 2) parasomnias, and 3) sleep disorders associated with medical and psychiatric conditions. In general, the categories of sleep disorders in the DSM-IV (American Psychiatric Association 1994) classification system are consistent with the ICSD-DCM categories. In ICSD-DCM, dyssomnias are defined as disorders of insufficient (in duration and quality), excessive, or inefficient sleep characterized by either difficulty in initiating and/or maintaining sleep or, in contrast, excessive sleepiness. The disorders of initiating and maintaining sleep, generically referred to as the insomnias, are associated with sleep that is insufficient to support good daytime functioning. The disorders of excessive somnolence, also known as the hypersomnias, are characterized by a persistent need for sleep that is excessive and leads to impaired daytime functioning. The ASDA coding manual further subclassifies dyssomnias into intrinsic (i.e., those that originate from causes within the body), extrinsic (i.e., those that require external factors to produce and maintain the disorder), and circadian (i.e., those characterized by inappropriate timing of sleep within the 24-hour day). A partial list of ICSD-DCM and DSM-IV dyssomnias that are commonly observed in children and adolescents is presented in Tables 17-1 and

17-2, respectively.

The parasomnias are defined by behaviors that intrude into the sleep process as a result of central or autonomic nervous system activation. Parasomnias are not primary disorders of sleep-wake organization. Rather, they represent disruptions of sleep continuity. In earlier nosologies, parasomnias were limited to disruptions that were most likely to occur during the early part of the night when Stage 4 NREM sleep was prominent. In both ICSD-DCM and DSM-IV, parasomnias have been expanded to include disruptions that occur in all states of sleep. The ICSD-DCM classification includes NREM sleep parasomnias, sleep-wake transition parasomnias, and REM sleep parasomnias, whereas the DSM-IV classification does not emphasize the sleep state in which the parasomnias occur. The ICSD-DCM and DSM-IV parasomnias that most commonly affect children and adolescents are listed in Tables 17-3 and

17-4, respectively. Again, concordance between the two systems is good.

The ICSD-DCM sleep disorders that co-occur most commonly with medical and psychiatric disorders of children and their DSM-IV equivalents are listed in

Tables 17-5 and 17-6, respectively. (The DSM-IV criteria for substance-induced sleep disorder are presented in

Table 17-7.) There are some differences in this category of disorder in the two nosologies in that DSM-IV maintains the multiaxial classification system originated in DSM-III (American Psychiatric Association 1980).

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Revision date: June 18, 2011
Last revised: by Amalia K. Gagarina, M.S., R.D.