Factor analysis and validation of the Disturbing Dreams and Nightmare Severity Index.

Abstract

The Disturbing Dream and Nightmare Severity Index (DDNSI) has been used widely in research and clinical practice without psychometric evidence supporting its use. The present study aimed to explore and confirm the factor structure of the DDNSI as well as to test the measure's construct validity and invariance between groups based on sex and race. In all, 2 samples of U.S. undergraduate participants (N = 614 and N = 606) provided data on nightmares (i.e., DDNSI, Nightmare Effects Survey, Nightmare Frequency Questionnaire, Nightmare Distress Questionnaire, and Trauma-Related Nightmare Survey) and related psychopathology (e.g., symptoms of insomnia, depression, posttraumatic stress disorder, and anxiety). Exploratory and confirmatory factor analyses found the 5 original items of the DDNSI to load onto a single latent factor. The DDNSI was found to be a valid measure of nightmare frequency and distress, as it was significantly correlated with the Nightmare Frequency Questionnaire and the Nightmare Distress Questionnaire, and the DDNSI was able to differentiate between nightmares and psychopathology. Multiple group analysis invariance testing found that the latent structure of the DDNSI was comparable between sex (male vs. female) and race (White vs. Black). Though this research comes nearly 2 decades after the initial creation and use of the DDNSI, it provides a foundation for the scientific rigor of previous and future studies on nightmares using the DDNSI.