Nightmares and self-injurious thoughts among clinically acute adolescents: Examining negative affect as a potential mechanism.

Nightmares, a specific sleep problem, have been associated with increased risk for suicidal and nonsuicidal self-injurious thoughts, yet mechanisms underlying this relationship remain poorly understood, particularly among adolescents. This study examined negative affect (NA) intensity as a potential mediator between nightmares and self-injurious thoughts in a clinically acute sample of adolescents. Adolescents (N = 86; M = 14.30; 48.8% white, 46.51% female) completed an ecological momentary assessment (EMA) study design for 28 days following discharge from acute psychiatric care for suicidal thoughts and behaviors. Daily sleep diaries were used to assess prior night nightmare presence and intensity. EMA was used to assess NA intensity, suicidal thought intensity, and nonsuicidal self-injurious thought intensity multiple times per day. Multilevel structural equation modeling revealed significant between-person mediation effects, whereby adolescents reporting more frequent and intense nightmares exhibited greater NA intensity, which, in turn, was associated with increased suicidal and nonsuicidal self-injurious thought intensity. Mediation effects were not observed at the within-person level, indicating that individual differences, rather than daily fluctuations in nightmares, accounted for these associations. Results identify NA intensity as a person-level mechanism linking nightmares and self-injurious thoughts. Future research should investigate additional mechanisms and employ temporally sensitive designs to clarify dynamic (within-person) processes underlying suicidal and nonsuicidal self-injurious thoughts in adolescents. This study underscores the clinical importance of addressing nightmares and NA intensity in clinically acute adolescents to inform suicide prevention efforts.