Psychometric Evaluation of the Insomnia Severity Index in U.S. College Students

Psychometric properties of the Insomnia Severity Index (ISI) were analyzed in U.S. college samples. ISI items and total score with sleep and psychosocial questionnaires were examined in Experiment I. ISI diagnostic accuracy in a clinical sample with and without insomnia was assessed in Experiment II. ISI test-retest validity, confirmatory factor analysis (CFA), and item response theory via graded response model (GRM) were assessed in Experiment III. Results indicated analogous ISI and sleep diary items showed moderate correlations (r