Reliability and Validity of Dysfunctional Beliefs About Sleep-2 (DBS-2), an Ultra-brief Rating Scale for Assessing Dysfunctional Thoughts About Sleep

Background and Objective It is important to consider dysfunctional beliefs about sleep when conducting cognitive-behavioral therapy for insomnia. The purpose of this study was to examine the reliability and validity of a Dysfunctional Beliefs about Sleep-2 items (DBS-2) scale in a general population and clinical sample.Methods Our study examined the reliability and validity of the DBS-2 scale in the general population (group I, n = 374) and in a clinical sample of subjects with insomnia disorders (group II, n = 105). An online survey targeting the general population was conducted over the course of January 10–18, 2022, and a retrospective study of medical records was conducted among a clinical sample of insomnia patients who visited the Asan Medical Center Sleep Clinic for the first time between September of 2021 and May of 2022. The internal consistency reliability of the DBS-2 scale was measured using split-half coefficients, and factor analysis was used to determine its validity. Using the Insomnia Severity Index (ISI) and the Dysfunctional Beliefs and Attitudes about Sleep-16 items (DBAS-16), convergence validity was explored.Results Split-half coefficients for the DBS-2 were 0.862 and 0.855 in the general population and a clinical sample of insomnia disorder. DBS-2 overall report score was significantly correlated with ISI (r = 0.26, p < 0.001) and DBAS-16 (r = 0.43, p < 0.001) in the general population, and correlated with ISI (r = 0.45, p < 0.001) and DBAS-16 (r = 0.50, p < 0.001) in the clinical sample. Both groups of subjects had an optimal cut-off score of 13 for the DBS-2 scale.Conclusions We found that the DBS-2 scale, a two-item ultra-brief rating scale, could accurately measure dysfunctional beliefs about sleep in the general population and a clinical sample of insomnia patients.