Psychometric properties of the Disturbing Dream and Nightmare Severity Index-Korean version

Abstract

Study Objectives: This study aimed to examine psychometric properties of the Disturbing Dream and Nightmare Severity Index (DDNSI) in individuals aged between 18 and 39. Methods: All participants (n = 674) were asked to complete the DDNSI, including the modified Nightmare Effects Survey. Additionally, 109 participants were tested for test-retest reliability after 3 months. Among our sample, 229 (33.9%) reported having at least 1 nightmare per month. Results: Internal consistency was evaluated for the total sample (Cronbach's α = .920) and separately for individuals reporting more than once per month (Cronbach's α = .755). Test-retest reliability after 3months was .705. Convergent validity of the DDNSI with Nightmare Effects Survey was also satisfactory (r =.638, P