Depression as a mediator between frequent nightmares and non-suicidal self-injury among adolescents: a 3-wave longitudinal model.

Abstract Background Frequent nightmares and depression are associated with non-suicidal self-injury (NSSI) in adolescents. Little is known about the mediating role of depression in the nightmare-NSSI link. This study explores the longitudinal mediating effect of depression on the relationship between frequent nightmares and NSSI as well as the moderating effect of gender using a three-wave longitudinal design. Methods Participants were adolescents from the Shandong Adolescent Behavior and Health Cohort who were surveyed at baseline, 1 year later, and 2 years later. A self-administered questionnaire was used to measure nightmare frequency, depression, and NSSI. Structural equation modeling and multiple-group analysis were used to test the mediating effect of depression and the moderating effect of gender. Covariates included demographics and earlier measures of depression and NSSI. Results Among 6995 participants, 3399 (48.6%) were females, mean age was 14.86 (SD = 1.50) years at baseline. Frequent nightmares had a significant mediation effect on NSSI through depression (Bab = 0.06, 95% CI = 0.02–0.10) after controlling for demographics and earlier measures of depression and NSSI. Gender had no significant moderating effect on the nightmare-NSSI association. Limitations All data were collected by self-report. Conclusions The association between frequent nightmares and NSSI in adolescents was partially mediated by depression. Frequent nightmares and depression should be assessed and treated to prevent self-harm in adolescents.