Factor Analysis and Validation of the Disturbing Dream and Nightmare Severity Index in an Inpatient Sample.

STUDY OBJECTIVES: The Disturbing Dream and Nightmare Severity Index (DDNSI) has been used widely in research and clinical practice without psychometric evidence supporting its use in clinical samples. The present study aimed to explore and confirm the factor structure of the DDNSI in an inpatient sample. We also sought to test the measure's construct validity.

METHODS: Two samples of U.S. inpatients including adult ( N  = 937) and adolescent ( N  = 274) participants provided data on nightmares (i.e. DDNSI), sleep quality (i.e. the Pittsburgh Sleep Quality Index) and related psychopathology symptoms (e.g. depression, posttraumatic stress disorder, anxiety).

RESULTS: Exploratory and confirmatory factor analyses found the six original items of the DDNSI to load onto a single latent factor.

CONCLUSIONS: The DDNSI was found to be a valid measure of nightmare frequency and distress, as it was significantly correlated with the items related to disturbing dreams, and the DDNSI was able to differentiate between nightmares and psychopathology symptoms. Though this research comes nearly two 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.