A prospective study of nightmare disorder among Chinese adults in Hong Kong: Persistence and mental health outcomes

Objectives: Previous studies showed that nightmares are prevalent and are associated with negative health outcomes. However, no empirical data is available demonstrating the extent to which nightmare disorder persists over time. Current literature provides a limited understanding of the trajectory and wider mental health outcomes of nightmare disorder. This longitudinal study examined the persistence and mental health outcomes of nightmare disorder. Methods: A total of 230 Hong Kong Chinese adults completed standardized assessments twice with an interval of about 6 months. Results: Over half (66.7%) of the participants with probable nightmare disorder at baseline remained to meet the DSM-5 criteria for the disorder at follow-up. Participants with probable nightmare disorder at baseline were significantly more likely to screen positive for PTSD (82.1% vs 18.3%) (p <.001) (p <.001), and they reported higher rates of mental health service usage at both timepoints (p =.001 to.003). Baseline nightmare disorder severity was negatively associated with subsequent self-rated mental health (β = -.151, p =.010) and self-esteem (β = -.141, p =.009) and it also predicted subsequent PTSD symptoms (β =.122, p =.012). Conclusions: This study provides first empirical data showing that nightmare disorder could be persistent over time. Nightmare disorder symptoms are associated not only with PTSD symptoms but also with a broader range of mental health issues. This study points to the public health importance of identifying and managing nightmare disorder symptoms in the community. Additionally, the presence of nightmare disorder symptoms may be a helpful indicator for identifying post-traumatic stress.