Validation of the Insomnia Severity Index among University Students in Korea

Abstract

Insomnia is the most common sleep complaint in clinical practice, affecting both the physical and mental health of patients as well as many aspects of their life quality. Young adults, especially university students, are prone to a high prevalence of poor sleep quality or insomnia. Accurate assessment of insomnia severity among university students has become an important issue. One promising screening tool to identify clinically significant insomnia in the campus setting is the Insomnia Severity Index (ISI), a seven-item self-report measure designed to assess the nature and severity of one’s insomnia. Although the ISI has been validated in primary care settings in Korea, no studies have examined its factor structure for university students. This study aimed to analyze the psychometric properties of the Korean version of the ISI. A convenience sample of 252 undergraduate students aged 18-64 attending a four-year university in South Korea was recruited for the study. The collected data underwent exploratory factor analysis (EFA) and confirmatory factor analysis (CFA), which tested alternative models to determine the factorial structure of the ISI. Internal consistency and convergent and discriminant validity were examined. CFA findings showed that a two-factor model best fit the data. The ISI was found to be significantly correlated with higher depressive symptoms and possess adequate internal consistency. Our study confirmed that the ISI had insufficient reliability and good convergent and discriminant validity. This study generally supports the validity and factor structure of the ISI. Its two-factor structure is a psychometrically robust measure for evaluating the prevalence of insomnia.