AbstractStudy ObjectivesNo study has yet examined the prevalence of frequent nightmares in representative youth populations in Asia and how they may contribute to future mental health risks. We aimed to fill this gap using data from a large-scale household-based youth sample in Hong Kong.MethodsParticipants were consecutively recruited from a large-scale epidemiological youth mental health study in Hong Kong (n = 3132). A subset of participants were invited for a follow-up assessment after 1 year (n = 1154 in the final analyses). Frequent nightmares (≥1/week during the past month) were assessed using an item from the Pittsburgh Sleep Quality Index. Univariate analyses and multivariable logistic regression models were applied to examine the contribution of frequent nightmares at baseline to moderate-to-severe depressive and anxiety symptoms, post-traumatic stress disorder symptoms, and 30-day major depressive episode (MDE) or generalized anxiety disorder (GAD), both at baseline and follow-up. The long-term functional implications of frequent nightmares were also examined.ResultsThe prevalence of frequent nightmares was 16.3%. Females were more likely to experience frequent nightmares (20.4%) compared to males (12.1%), p < 0.001. Baseline frequent nightmares were significantly associated with all four mental health outcomes at 1 year. Notably, their prospective associations with depressive and anxiety symptoms and 30-day MDE/GAD remained significant even after adjusting for external stressors, resilience, and sociodemographic characteristics. Frequent nightmares were also significantly associated with both current and 1-year functional impairments.ConclusionsFrequent nightmares have significant long-term implications on mental health and functioning. Identifying young adults with frequent nightmares can improve early risk detection and intervention in the population.