Validity and reliability of Insomnia Severity Index among older adults in Indonesia

Background Insomnia is a prevalent sleep disorder among older adults, associated with fatigue, cognitive decline, and poor physical and mental health. Concise instruments such as the Insomnia Severity Index (ISI) are valuable for screening and evaluation. This study aimed to validate the Indonesian version of the ISI in older adults. Methods This study used a cross-sectional survey conducted in multiple health centers and hospitals. The ISI was adapted into Indonesian following the Consensus-based Standards for the Selection of Health Measurement Instruments guidelines. Construct validity was examined using Exploratory Factor Analysis, while reliability was assessed using Cronbach’s alpha and intraclass correlation coefficients (ICC). Results A total of 510 older adults (mean age 69.3 years, 81.4% female) participated. Item–total correlations were strong ( r ≥ 0.75, p < 0.01), supporting internal consistency. Factor analysis confirmed a unidimensional structure (Kaiser-Meyer-Olkin = 0.92; Bartlett’s test p < 0.01). The ISI showed excellent reliability (Cronbach’s alpha = 0.96; ICC = 0.96). Conclusion This study demonstrates that the ISI is a valid and reliable instrument for evaluating perceived insomnia severity among older adults in Indonesia. Its ease of use and strong psychometric properties make it an invaluable tool for healthcare practitioners in routine screening and clinical practice.