Development of the Brief Questionnaire Version of the Discrepancy Between Desired Time in Bed and Desired Total Sleep Time Index: The DBSTq-2

Background and Objective The aim of this study was to develop a modified questionnaire version of the discrepancy between desired time in bed and desired total sleep time (DBST) index, while addressing its limitations.Methods Two online surveys were conducted; one among the general population and another among individuals reporting insomnia symptoms. Participants provided sleep-related data and completed rating scales including the Insomnia Severity Index (ISI), Patient Health Questionnaire-2 (PHQ-2), and Dysfunctional Beliefs and Attitudes about Sleep-6 (DBAS-6). Based on the analysis of significant items, a questionnaire version of the DBST index was developed. Statistical analyses including correlation analysis, linear regression, and mediation analysis were performed.Results A total of 1,031 participants were included in the analysis from two studies. In both studies, the DBST index showed significant correlations with the ISI and DBAS-6 (all p<0.01). Two items were selected and developed into the DBSTq-2. In both studies, the DBSTq-2 score was significantly correlated with the ISI, PHQ-2, and DBAS-6 (all p<0.01). Mediation analyses reveal that both DBST index and DBSTq-2 had a direct effect on the ISI, with DBAS-6 and PHQ-2 mediating the relationship. The optimal cutoff score for the DBSTq-2 to identify participants reporting insomnia was estimated at ≥5.25 (specificity, 75.7%; sensitivity, 63.5%).Conclusions The DBSTq-2, a questionnaire version of the DBST index, was developed to improve its applicability while addressing its limitations.