Am J Psychiatry 1997; 154:1412-1416
Copyright © 1997 by American Psychiatric Association
Clinical factors contributing to the differential diagnosis of primary insomnia and insomnia related to mental disorders
PD Nowell, DJ Buysse, CF Reynolds 3rd, PJ Hauri, T Roth, EJ Stepanski, MJ Thorpy, E Bixler, A Kales, RL Manfredi, AN Vgontzas, DM Stapf, PR Houck and DJ Kupfer
Sleep and Chronobiology Center, Western Psychiatric Institute and Clinic, University of Pittsburgh School of Medicine, USA.
OBJECTIVE: Primary insomnia and insomnia related to mental disorders are
the two most common DSM-IV insomnia diagnoses, but distinguishing between
them is difficult in clinical practice. This analysis was performed to
identify clinical factors used by sleep specialists to distinguish primary
insomnia from insomnia related to mental disorders. METHOD: Clinicians
evaluated 216 patients referred for insomnia at five clinical sites, rated
a list of clinical factors judged to contribute to each patient's
presentation, and assigned diagnoses. Analysis of variance was performed,
with contributing factors as the dependent variable and diagnostic group
and clinic location as independent variables. RESULTS: Sleep specialists
rated a psychiatric disorder as a stronger factor for insomnia related to
mental disorders and rated negative conditioning and sleep hygiene as
stronger factors for primary insomnia. However, a psychiatric disorder was
rated as a contributing factor for 77% of patients who received a first
diagnosis of primary insomnia. CONCLUSIONS: While neither sleep hygiene nor
negative conditioning is a diagnostic criterion in DSM-IV, these results
support the face validity of these clinical factors distinguishing between
primary insomnia and insomnia related to mental disorders. The use of a
psychiatric disorder as an inclusion criterion for insomnia related to
mental disorders and an exclusion criterion for primary insomnia reinforces
a categorical distinction between the two diagnoses, but the contribution
of psychiatric symptoms in primary insomnia appears to be a clinically
relevant one. These findings suggest the need for studies on the validity
of negative conditioning and sleep hygiene in the etiology of primary
insomnia, as well as on the significance of psychiatric disorders,
especially depression, in primary insomnia.
