Psychometric Evaluation of the Insomnia Severity Index in Nurses

ABSTRACT

Objectives

Examine psychometric properties of the Insomnia Severity Index (ISI) in a sample of nurses.

Method

In a sample of day shift nurses (N = 289), a confirmatory factor analysis (CFA), convergent and discriminant validity analyses, and a test–retest reliability analysis were performed.

Results

CFA showed that a two-factor model provided the best fit. The ISI had moderate to poor convergent validity with sleep diary parameters, and moderate convergent validity with the Sleep Condition Indicator (r = -.66), Pittsburgh Sleep Quality Index (r = .66), and PROMIS Sleep-Related Impairment measure (r = .67). The ISI demonstrated good discriminant validity with the measures Composite Scale of Morningness (r = −.27), Nightmares Disorder Index (r = .25), PTSD Checklist for DSM-5 (sleep items removed; r = .32), and Perceived Stress Scale (r = .43). The ISI had weaker discriminant validity with the PHQ-9 (r = .69) and Generalized Anxiety Disorder Screener (r = .51). The ISI demonstrated a good test–retest reliability (ICCs = .74–.88).

Conclusions

The ISI is a psychometrically strong measure for the assessment of insomnia severity in day shift nurses. Overlap with psychological symptoms, primarily anxiety and depression, suggests caution while interpreting these constructs.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary Material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15402002.2024.2362370.

Additional information

Funding

The study was performed at the University of North Texas, Denton, TX. This was not an industry supported study. This study was supported by a grant from the National Institute of Allergy and Infectious Diseases (R01AI128359). The authors have seen and approved this manuscript. Dr. Emert is partially funded by NIA (2R44AG056250-03A1). Dr. Taylor is partially funded by NIA (2R44AG056250-03A1) and FEMA (DHS-20-GPD-044-000-97). Dr. Dietch is partially funded by NHLBI (1K23HL157698). The authors have indicated no financial conflicts of interest in relation to this manuscript.