Life stress and suicidality mediated by insomnia and depressive symptoms in adolescents: a three-wave longitudinal study

Study Objectives Little empirical work has investigated the associations between life stress (LS), insomnia, depression, and suicidality in multi-wave longitudinal studies. With three waves of data collection 1-year apart, this longitudinal study with a large sample of adolescents examined the predicting effects of LS on suicidality 1-year later and 2 years later and the mediating roles of insomnia and depression in the LS-suicidality link. Methods A total of 6995 adolescents (mean age = 14.86 years, 51.4% male) participated in a three-wave longitudinal study of behavior and health in Shandong, China. A self-administered structured questionnaire and standardized scales were used to assess suicidality (including suicidal thought [ST], suicide plan [SP], and suicide attempt [SA]), LS, insomnia, and depression in 2015 (T1), 1-year later (T2), and 2 years later (T3). Mediation effects were examined with path models. Results The overall prevalence rates of past-year suicidality were 13.4% at T1, 10.0% at T2, and 9.5% at T3, respectively. The prevalence rates of suicidality across T1-T3 significantly increased with elevated levels of baseline LS, insomnia, and depression (p < .001). Path models indicated that the relationship between baseline LS and suicidal ideation (i.e., ST/SP) 2 years later was significantly mediated by both insomnia and depression. Depression was also a significant mediator between LS and SA. Conclusions LS is a significant predictor of suicidality 1-2 years later in adolescents. Depression mediates the association between LS and suicidal ideation and suicide attempt while insomnia appears to be a mediator for suicidal ideation rather than suicide attempt.