An investigation of interpretive bias in insomnia: an analog study comparing normal and poor sleepers

STUDY OBJECTIVES: Cognitive theories state that psychological disorders are associated with, and are possibly maintained by, interpretive biases, which are tendencies to make threatening interpretations of ambiguous stimuli. Recent models of insomnia have highlighted the importance of cognitive processes. The aim of this study was to empirically evaluate whether an interpretive bias is present in poor sleepers. DESIGN: A mixed-design analysis of covariance was employed with group (normal sleepers vs poor sleepers) as a between-subjects variable and sentence type (insomnia-related vs anxiety related) as a within-subjects variable. The dependent variables were the extent to which participants interpreted insomnia-related and anxiety-related sentences as having a threatening meaning. Sleepiness was used as a covariate. SETTING: Treatment and research clinic at a university department of psychiatry. PARTICIPANTS: Forty-one normal and 34 poor sleepers. MEASUREMENTS AND RESULTS: A set of ambiguous scenarios were administered to participants who gave open-ended and forced-choice interpretations of the scenarios. Each scenario could be interpreted in a threat (insomnia or anxiety)-related or neutral manner. Even after controlling for sleepiness, poor sleepers were found to make significantly more threat-related interpretations of ambiguous scenarios than did normal sleepers. CONCLUSIONS: These findings suggest that there is a bias toward threat-related interpretations among poor sleepers and that the exploration of biased interpretations may be an important avenue for future research among individuals who meet full diagnostic criteria for insomnia.