Place of chronic insomnia in the course of depressive and anxiety disorders.
BACKGROUND
Insomnia is frequent in the general population and is often related to a psychiatric illness. However, little is known about how the chronicity of insomnia affects this relation and how often subjects with chronic insomnia have antecedents of psychiatric disorders.


METHODS
A total of 14,915 subjects aged from 15 to 100 years representative of the general population of the United Kingdom, Germany, Italy, and Portugal were interviewed by telephone using the Sleep-EVAL system. The questionnaire assessed current psychiatric disorders according to the DSM-IV classification and a series of questions assessed the psychiatric history. Insomnia was considered as chronic when it lasted for 6 months or more.


RESULTS
The prevalence for insomnia accompanied with impaired daytime functioning was 19.1% and significantly increased with age. More than 90% of these subjects had a chronic insomnia. About 28% of subjects with insomnia had a current diagnosis of mental disorders and 25.6% had a psychiatric history. A DSM-IV insomnia disorder was found in 6.6% of the sample. Presence of severe insomnia, diagnosis of primary insomnia or insomnia related to a medical condition, and insomnia that lasted more than one year were predictors of a psychiatric history. In most cases of mood disorders, insomnia appeared before (> 40%) or in the same time (> 22%) than mood disorder symptoms. When anxiety disorders were involved, insomnia appeared mostly in the same time (>38%) or after (> 34%) the anxiety disorder.


CONCLUSIONS
The study shows that psychiatric history is closely related to the severity and chronicity of current insomnia. Moreover, chronic insomnia can be a residual symptom of a previous mental disorder and put these subjects to a higher risk of relapse.
Ohayon
Maurice M
MM
Stanford Epidemiology Sleep Research Center, Stanford University, 401 Quarry Road Suite 3301, School of Medicine, Stanford, CA 94305, USA. mohayon@stanford.edu
Roth
Thomas
T
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001008:Anxiety Disorders / Q000145:classification / Q000175:diagnosis / Q000209:etiology*; D002908:Chronic Disease; D003430:Cross-Sectional Studies; D003866:Depressive Disorder / Q000145:classification / Q000175:diagnosis / Q000209:etiology*; D003937:Diagnosis, Differential; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005060:Europe / Q000453:epidemiology; D005260:Female; D006306:Health Surveys; D006801:Humans; D007407:Interviews as Topic / Q000379:methods; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D007319:Sleep Initiation and Maintenance Disorders / Q000145:classification* / Q000150:complications* / Q000175:diagnosis / Q000517:prevention & control; D011795:Surveys and Questionnaires; D013997:Time Factors