Academic journal article Journal of Cognitive Psychotherapy

Candidate Cognitive Processes in Psychophysiologic Insomnia

Academic journal article Journal of Cognitive Psychotherapy

Candidate Cognitive Processes in Psychophysiologic Insomnia

Article excerpt

In this review, we begin by highlighting the lack of available evidence to support current diagnostic criteria for psychophysiologic insomnia. We then outline 3 new testable candidate cognitive processes in psychophysiologic insomnia: attention bias, sleep effort, and metacognitive beliefs. Each candidate element is carefully described. Evidence of involvement in insomnia maintenance is discussed based on the existing literature. The need for an experimental research agenda to examine the interplay of these candidate cognitive processes is then emphasized. Research ideas are presented throughout our discussions.

Keywords: psychophysiologic insomnia; cognitive-behavior therapy; attention bias; metacognition

In this article we review evidence concerning current diagnostic criteria for psychophysiologic insomnia. These diagnostic criteria reflect expert consensus opinion and guide clinical and research practice, but continue to lack substantive empirical support. We then emphasize the need for experimental cognitive research, highlighting three candidate cognitive elements we believe may contribute significantly to the persistence of psychophysiologic insomnia.

How DO THE MAJOR CLASSIFICATION SYSTEMS CONCEPTUALIZE INSOMNIA?

The Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) defines "primary insomnia" as a disorder of difficulty initiating and/or maintaining sleep or of nonrcstorativc sleep lasting at least 1 month (American Psychiatric Association, 1994). The International Classification of Sleep Disorders-Revised (ICSD-R) uses the term "psychophysiologic insomnia" (American Sleep Disorders Association, 1997). Both systems emphasize the importance of impaired daytime functioning. An update of these latter criteria (ICSD-2) are in final preparation and are likely to be published by the American Academy of Sleep Medicine in 2005.

Certain aspects of classification have stood the test of time. For example, primary/psychophysiologic insomnia remains a diagnosis largely by exclusion (of respiratory or muscular disturbance, known medical or psychiatric disorder, pain). Objective markers have been elusive, although in psychophysiologic insomnia, the sufferer's subjective sleep complaint is often verified objectively using polysomnographic (PSG) assessment. This contrasts with the disorder known as sleep state misperception (ICSD-R), likely to be termed paradoxical insomnia in ICSD-2, where a complaint of severe insomnia occurs without evidence of objective sleep disturbance and without the level of daytime impairment commensurate with the degree of sleep deficits reported. This article focuses specifically upon psychophysiologic insomnia. We use the abbreviation PI to refer to psychophysiologic insomnia. We acknowledge different mechanisms and models may be required to understand the very large subjective-objective discrepancies found in sleep state misperception.

The conceptual basis of PI, as an intrinsic sleep disorder, is likely to remain the same in ICSD-2, that is of "heightened physiological arousal and/or conditioned sleep difficulty in bed." Although treatments designed to address heightened physiological (e.g., progressive muscular relaxation) or mental arousal (e.g., cognitive interventions), or to address inappropriate sleep/ wake conditioning (e.g., stimulus control therapy [SC]) in insomnia patients have been found to be effective (Chesson et al., 1999) we have limited evidence, either that such factors are specific to the development and persistence of insomnia, or that such treatments operate by counteracting them. Indeed, it is through experimental studies and other research, rather than treatment studies, that theory and clinical practice are best advanced. Treatment effectiveness often tells us nothing about disorder maintenance (Salkovskis, 2002).

THE EVIDENCE FOR HEIGHTENED PHYSIOLOGICAL AROUSAL

Monroe (1967) compared 16 good sleepers with 16 poor sleepers, and noted poor sleepers exhibit heightened autonomic arousal (higher rectal temperature, vasoconstrictions per minute, perspiration rate, skin conductance, body movements per hour) both prior to and during sleep. …

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