Elsevier

Clinical Psychology Review

Volume 21, Issue 7, October 2001, Pages 1037-1059
Clinical Psychology Review

INSOMNIA: SYMPTOM OR DIAGNOSIS?

https://doi.org/10.1016/S0272-7358(00)00083-0Get rights and content

Abstract

Is insomnia a clinical entity in its own right or is it simply a symptom of an underlying medical or psychological disorder? The widely held view among many clinicians and researchers is that insomnia is secondary to or an epiphenomenon of a ‘primary’ medical or psychological disorder. Consequently, insomnia ‘symptoms’ have tended to be trivialized or ignored. This paper aims to highlight the assumptions and implications of distinguishing between ‘primary’ and ‘secondary’ insomnia and reviews the evidence for the distinction by considering (1) issues relating to the diagnosis and classification of insomnia, (2) whether insomnia is a symptom of other medical and psychological disorders, (3) whether insomnia is comorbid with other disorders, (4) whether insomnia is ‘secondary’ to other disorders, and (5) whether insomnia occurs in the absence of comorbidity. It is concluded that viewing insomnia as a symptom or epiphenomenon of other disorders can be unfounded. This view may deprive many patients of treatment, which might not only cure their insomnia, but may also reduce symptoms associated with the assumed ‘primary’ disorder. Finally, directions for future research to further illuminate the relationship between insomnia and comorbid disorders are discussed.

Section snippets

DEFINITION OF INSOMNIA

There are three diagnostic schedules that present diagnostic criteria for insomnia; the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV; American Psychiatric Association, 1994), the International Classification of Sleep Disorders, Revised (ICSD-R; American Sleep Disorders Association, 1997), and the International Classification of Diseases, 10th Edition (ICD-10; World Health Organization, 1992). The diagnostic criteria for insomnia across the three classificatory

IS INSOMNIA A SYMPTOM OF OTHER DISORDERS?

Although this section will begin by discussing insomnia as a symptom of physical illness, most of the discussion in the present paper will center on insomnia and its relationship to psychological disorder. The reason for this emphasis is two-fold; insomnia as a symptom of a psychological disorder is 10 times more frequent than insomnia related to a physical illness (Ford & Kamerow, 1989) and the association between insomnia and psychological disorder raises important questions relating to cause

IS INSOMNIA COMORBID WITH OTHER DISORDERS?

The answer to this question relies on studies that have included an assessment of the prevalence of insomnia along with an assessment of the presence of a range of other psychological disorders. Unfortunately, the number of studies reporting comorbidity between insomnia and other disorders is limited as insomnia is typically not assessed in epidemiologic studies (Canals et al., 1997). Possible accounts of this omission include: (1) the assumption that insomnia is trivial and secondary to other

IS INSOMNIA SECONDARY TO OTHER DISORDERS?

The evidence reviewed thus far indicates that insomnia is a symptom of a range of medical and psychological disorders and is often comorbid with a range of other psychological disorders. Does being a symptom and a commonly comorbid disorder necessarily relegate insomnia to the role of ‘secondary’ diagnosis? It may be helpful to examine the precedent set by high comorbidity between other psychological disorders. Canals et al. (1997) reported high levels of comorbidity between all disorders

DOES INSOMNIA EVER OCCUR WITHOUT A COMORBID DISORDER?

Evidence that a significant proportion of insomnia cases occur in the absence of comorbidity would further strengthen the case against insomnia being the ‘secondary’ disorder and conversely, would strengthen the case for it being an important clinical entity in its own right. Several studies have reported high rates of insomnia without any comorbidity. The rate of insomnia in the absence of another psychological disorder is 10% in a community adult sample (Ford & Kamerow, 1989), 54% of a sample

FUTURE DIRECTIONS

With some exceptions (Weissman et al., 1997), the literature has been dominated by an almost exclusive focus on comorbidity between mood disorders and insomnia. It is critical that research assessing longitudinal relationships be expanded to include investigation of insomnia and a range of psychological disorders. In particular, the proposal that somatization plays a mediating role in the relationship between insomnia and comorbid psychological disorders (Frisoni, de Leo, Rozzini, & Bernardini,

CONCLUSION

Insomnia has been widely regarded as ‘secondary’ to or an epiphenomenon of another psychological disorder. This paper has presented evidence suggesting that insomnia is indeed a symptom of and comorbid with a range of psychological disorders. However, the idea that this implies that insomnia is ‘secondary’ is unfounded as: (1) depression is predicted by the presence of prior insomnia, (2) an effective intervention for the primary disorder does not necessarily alleviate the insomnia, and (3)

References (65)

  • A.J. Spielman et al.

    A behavioral perspective on insomnia treatment

    Psychiatric Clinics of North America

    (1987)
  • M.B. Stein et al.

    Sleep impairment in patients with social phobia

    Psychiatry Research

    (1993)
  • M.M. van Moffaert

    Sleep disorders and depression: the ‘chicken and egg’ situation

    Journal of Psychosomatic Research

    (1994)
  • J.C. Wakefield

    Philosophy of science and the progressiveness of the DSM's theory-neutral nosology: response to Follette and Houts, part 1

    Behaviour Research and Therapy

    (1999)
  • M.M. Weissman et al.

    The morbidity of insomnia uncomplicated by psychiatric disorders

    General Hospital Psychiatry

    (1997)
  • Diagnostic and statistical manual of mental disorders

    (1994)
  • The international classification of sleep disorders, revised

    (1997)
  • S. Ancoli-Israel et al.

    Characteristics of insomnia in the United States: results of the 1991 National Sleep Foundation Survey I

    Sleep

    (1999)
  • A.B. Beeder et al.

    Treatment strategies for comorbid disorders: psychopathology and substance abuse

  • R.M. Benca et al.

    Sleep and psychiatric disorders. A meta-analysis

    Archives of General Psychiatry

    (1992)
  • R.M. Berlin et al.

    Sleep disorders on a psychiatric consultation service

    American Journal of Psychiatry

    (1984)
  • F.C. Blais et al.

    Treatment of comorbid insomnia and generalized anxiety disorder

    Sleep

    (2000)
  • M.H. Bonnet et al.

    Diagnosis and treatment of insomnia

    Respiratory Care Clinics of North America

    (1999)
  • K.T. Brady

    Posttraumatic stress disorder and comorbidity: recognizing the many faces of PTSD

    Journal of Clinical Psychiatry

    (1997)
  • N. Breslau et al.

    Daytime sleepiness: an epidemiological study of young adults

    American Journal of Public Health

    (1997)
  • R.A. Bryant et al.

    Acute stress disorder: a handbook of theory, assessment, and treatment

    (2000)
  • D.J. Buysse et al.

    Clinical diagnoses in 216 insomnia patients using the International Classification of Sleep Disorders (ICSD), DSM-IV and ICD-10 categories: a report from the APA/NIMH DSM-IV field trial

    Sleep

    (1994)
  • J. Canals et al.

    Prevalence of DSM-III-R and ICD-10 psychiatric disorders in a Spanish population of 18-year-olds

    Acta Psychiatrica Scandinavia

    (1997)
  • M.J. Chambers et al.

    Alert insomniacs: are they really sleep deprived?

    Clinical Psychology Review

    (1993)
  • A. Chesson et al.

    Practice parameters for the evaluation of chronic insomnia

    Sleep

    (1999)
  • H. Chevalier et al.

    Evaluation of severe insomnia in the general population: results of a European multinational survey

    Journal of Psychopharmacology

    (1999)
  • F. Cirignotta et al.

    Insomnia: an epidemiological survey

    Clinical Neuropharmacology

    (1985)
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