Reliability and validity of the Chinese version of the Nightmare disorder index in adolescents.

The Nightmare Disorder Index Questionnaire (NDI) was developed to measure the impact of nightmares. The purpose of this study was to investigate the psychometric properties of NDI among Chinese adolescents. This study investigated the validity and internal consistency of the Nightmare Disorder Index Chinese (NDI-CV) among 6014 Chinese adolescents who completed the NDI-CV, Nightmare Distress Questionnaire-Chinese Version (NDQ-CV), Pittsburgh Sleep Quality Index (PSQI), Insomnia Severity Index (ISI), Chinese Adolescent Daytime Sleepiness Scale (CADSS), Generalized Anxiety Disorder-7 Questionnaire (GAD-7), and Patient Health Questionnaire-9 (PHQ-9). In addition, we investigated the test-retest reliability of the NDI-CV among 423 adolescents who completed a retest of the NDI-CV after a 2-week interval. Finally, NDI-CV demonstrated good psychometric properties in a sample of Chinese adolescents (Cronbach's α coefficient of 0.876), and the 95% confidence interval for the 2-week retest correlation coefficient was 0.675-0.977 (p < 0.001).