What Does Nightmare Distress Mean? Factorial Structure and Psychometric Properties of the Nightmare Distress Questionnaire (NDQ)

Nightmares are extremely dysphoric dreams. But nightmare distress, and not the mere frequency of nightmares, is associated with well-being and psychopathology. Nightmare distress has been conceptualized in different ways: (a) nightmare intensity, (b) nightmare effects, (c) nightmare related symptoms, and (d) the perception of nightmare distress. The Nightmare Distress Questionnaire (NDQ) is the most often used questionnaire to capture nightmare distress. However, there is insufficient information about its psychometric properties and it remains unclear what exactly it measures. In order to investigate the psychometric quality and factorial structure of this questionnaire, 213 men and women suffering from recurrent nightmares filled in the German version of the NDQ, as well as depression (Center for Epidemiologic Studies Depression Scale, CES-D) and sleep quality (Pittsburgh Sleep Quality Inventory, PSQI) measures. The reliability of the NDQ was good (alpha = .80). We identified 3 subscales, which explained 52% of the total variance: (a) general nightmare distress, (b) impact on sleep, and (c) impact on daytime reality perception. We found moderate correlations between nightmare distress scores, nightmare frequency, depression, and sleep quality. The psychometric properties of the NDQ are good. The questionnaire captures the general perception whether nightmares are evaluated as distressing, as well as nightmare related symptoms.