Associations between internet addiction and suicidal ideation in depressed adolescents: the mediating effect of insomnia as well as sex differences

Background Insomnia may mediate the association between internet addiction (IA) and suicidal ideation (SI). However, such association has not been thoroughly investigated in adolescents with major depressive disorder (MDD). Thus, our study aimed to explore whether insomnia significantly affects the association between IA and SI in adolescents with MDD, as well as any sex differences. Methods From January 2021 to September 2023, this cross-sectional study included 502 adolescents with MDD and 123 healthy controls (HCs). The Clinical Global Impression-Severity (CGI-S), the Internet Addiction Test (IAT), the Insomnia Severity Index Scale (ISI) and the Positive and Negative Suicidal Ideation Scale (PANSI) were used to assess subjects' severity of depression, IA, insomnia and SI. And we employed the PROCESS macro program to examine the mediating role of insomnia between IA and SI. Results Compared to HCs, adolescents with MDD had significantly higher levels of SI and their prevalence of IA and insomnia were 50.0% and 35.7%. In patients, PANSI scores correlated negatively with age and age of onset, and positively with disease duration as well as the scores of the CGI-S, IAT, and ISI (all p < 0.01). Moreover, above-mentioned correlations were more significant in girls. Mediation analyses showed that insomnia mediated the effect of IA on SI, and the total, direct, and indirect effects were 0.197 (95% CI: 0.132-0.262), 0.157 (95% CI: 0.096-0.218) and 0.040 (95% CI: 0.014-0.068), respectively. In female patients, the total, direct, and indirect effects were 0.224 (95% CI: 0.151-0.296), 0.191 (95% CI: 0.124-0.257) and 0.033 (95% CI: 0.002-0.068), respectively. In male patients, insomnia acted as a fully mediated effect between IA and SI, with an effect value of 0.045 (95% CI: 0.008-0.093). Conclusion Depressed adolescents have higher suicide risk, and SI is significantly associated with IA and insomnia, especially in girls. Moreover, insomnia may mediate the association between IA and SI. However, given the small sample size of this study and the limitations of assessment tools used, the results need to be viewed with caution. Regardless, clinical interventions should be strengthened for IA and insomnia in adolescents with MDD to reduce suicide risk.