Insomniacs' attributions: psychometric properties of the Dysfunctional Beliefs and Attitudes about Sleep Scale and the Sleep Disturbance Questionnaire

Objective: Mental overactivity has been widely implicated in the developmen t and maintenance of insomnia, making the accurate and valid measurement of cognitive variables of some importance. The purpose of this study was to i nvestigate the psychometric properties of two existing attributional scales . Methods: Data are presented from 178 clinic attending insomniacs who comp leted the Dysfunctional Beliefs and Attitudes about Sleep Scale (DBAS) and the Sleep Disturbance Questionnaire (SDQ). Standard procedures for the psyc hometric evaluation of scales were adopted. Results: The internal consisten cy of the DBAS (30 items) was reasonable (Cronbach's alpha = 0.72); however , a revised ten-item short form (DBAS-10) demonstrated a more robust princi pal component structure than the original scale (three relatively "pure" fa ctors explained 55% of the variance). The derived subscales achieved satisf actory internal consistency, and the DBAS-10 demonstrated treatment-related measurement sensitivity. The DBAS-10, nevertheless, correlated highly (r = 0.826) with the DBAS. A four-factor solution for the SDQ is also presented (61% explained variance) with alpha = 0.67. Internal consistency of these subscales ranged from 0.59 to 0.82. The association between the SDQ and DBA S-10 was modest (r = 0.28), suggesting that the scales have some independen ce. Conclusions: The scales offer potential for clinical and research work on insomnia and possible applications are discussed. (C) 2000 Elsevier Scie nce Inc. All rights reserved.