Polish validation of the Sleep Condition Indicator (SCI-PL) for screening insomnia disorder based on DSM-5 criteria

Abstract Insomnia disorder (ID) is a highly prevalent sleep disorder imposing a substantial socioeconomic burden. However, there is no screening tool for assessing ID based on DSM-5 criteria adapted to the Polish cultural setting. The aim of the current study was to translate, adapt and validate the Sleep Condition Indicator (SCI), which screens for ID based on DSM-5 criteria, in a Polish population. The SCI was translated into Polish and administered to a quota-random sample of 1,282 respondents from the Polish adult population balanced with respect to gender, age, and place of residence and recruited through an online panel. No clinical diagnostic interview for ID was conducted. Participants also completed the Athens Insomnia Scale (AIS) and the Pittsburgh Sleep Quality Index (PSQI). Exploratory factor analysis supported a one-factor structure, and confirmatory factor analysis demonstrated acceptable fit for an essentially unidimensional model after accounting for correlated residuals among daytime-functioning items. The Polish SCI (SCI-PL) demonstrated high reliability (McDonald’s ω = 0.887). Convergent validity indicated strong negative correlations with the AIS (-0.83) and the PSQI (-0.80) ( p < .001), supporting external construct validity. Overall, the SCI-PL demonstrates strong psychometric properties and appears to be a suitable tool for the initial screening of ID.