The mediating role of somatic depressive symptoms in the relationship between adverse childhood experiences and insomnia severity

Background and aims: Early interpersonal trauma (EIT) has lasting effects on psychological functioning, especially depression, and is linked to emotion regulation impairments and sleep disruption. This study examined the role of these factors in patients with insomnia disorder (PsWID). Methods: Eighty PsWID and 78 controls completed the Traumatic Experiences Checklist (TEC), the Beck Depression Inventory–II (BDI-II), and the Difficulties in Emotion Regulation Scale (DERS); PsWID also completed the Insomnia Severity Index (ISI). Group differences in TEC, BDI-II, and DERS scores were examined, and measures showing significant differences were correlated with ISI scores in PsWID. Multiple linear regression was then conducted to identify predictors of insomnia severity, followed by mediation analyses. Results: Compared with controls, PsWID reported higher BDI-II total, cognitive–affective, and somatic subscale scores, as well as higher TEC emotional neglect and impact (Imp) subscale scores. In PsWID, ISI scores were positively associated with TEC-Imp and BDI-II total and subscale scores. Regression analyses showed that the TEC-Imp and BDI-II somatic factor were the only significant predictors of insomnia severity. Mediation analyses indicated that the TEC-Imp–ISI relationship was partially mediated by somatic depressive symptoms. Discussion: Results showed that EIT influences insomnia severity both directly—through disruption of homeostatic regulation—and indirectly, via somatic depressive symptoms that amplify perceived insomnia severity in PsWID. Conclusions: These results highlight the importance of considering EIT and psychological functioning in PsWID. Integrating trauma- and depression-informed approaches into insomnia treatment may improve both sleep and psychological well-being.