Validation of the Korean version of the Sleep, Circadian Rhythms, And Mood (SCRAM) questionnaire

This study aimed to develop the Korean version of the Sleep, Circadian Rhythms, and Mood (SCRAM) questionnaire and to evaluate its reliability and validity. An online survey was conducted among the general population between 16 June and 24 June 2025. Of the 600 respondents, 528 were analysed. Exploratory factor analysis was performed on Sample I (N = 265), and confirmatory factor analysis (CFA) on Sample II (N = 263). The item-response theory (IRT) framework, including the Rasch model and graded response model, was employed to examine the item-level properties. Convergent validity was assessed using the Insomnia Severity Index, Patient Health Questionnaire-9, Glasgow Sleep Effort Scale, Adaptive Cognition and Behaviors About Sleep-6, the DBST index, and sleep indices. Exploratory factor analysis supported a three-factor structure of Good Sleep, Morningness, and Depressed Mood. CFA supported a good model fit for the three-factor structure of the SCRAM (CFI = 0.987, TLI = 0.985, RMSEA = 0.062, and SRMR = 0.049). Under the IRT framework, the SCRAM questionnaire demonstrated good psychometric properties across its three latent dimensions. The internal consistency of each factor of the Korean version of the SCRAM was good, with Cronbach's alpha values of 0.876, 0.873, and 0.924, respectively. The alpha of the total 15 items was 0.698. The SCRAM also showed good convergent validity with other rating scales and sleep indices. The Korean version of the SCRAM and its three factor structure demonstrated good reliability and validity for assessing sleep, circadian rhythms, and mood states.