Psychometric Properties of the Korean Version of the Glasgow Sleep Effort Scale in the General Population and Among Individuals Reporting Insomnia

OBJECTIVE: This study aims to explore the psychometric properties of the Korean version of the Glasgow Sleep Effort Scale (GSES) using item response theory among both the general population and individuals who report insomnia. METHODS: We aimed to collect 300 individuals from the general population for Study I and 600 from the general population complaining of insomnia for Study II. Psychometric properties of the GSES were assessed using confirmatory factor analysis (CFA) and item response theory. Convergent validity was examined with the Insomnia Severity Index, Dysfunctional Beliefs and Attitudes about Sleep-6, Patient Health Questionnaire-9, sleep indices, and the discrepancy between desired time in bed and desired total sleep time index. RESULTS: A total of 208 participants from Study I and 477 from Study II were ultimately analyzed. CFA for the single-factor model of the GSES showed a good fit in both Study I (comparative fit index [CFI]=0.986, Tucker-Lewis index [TLI]=0.980, root-mean-square error of approximation [RMSEA]=0.066, standardized root-mean-square residual [SRMR]=0.043) and Study II (CFI=0.990, TLI=0.986, RMSEA=0.081, SRMR=0.057). The GSES demonstrated strong psychometric properties under both the Rasch and graded response models, with good item fit, high reliability, and effective discrimination across a range of ability levels. Some items provided limited information, indicating that future validation should explore underutilized response categories and include more diverse samples. The GSES was significantly correlated with other rating scales in both Studies I and II. CONCLUSION: The Korean version of the GSES is a reliable and valid instrument for assessing individuals' anticipatory concerns regarding sleep.