Insomnia beyond emotion regulation in adolescent anxiety and depression: A severity-based analysis

Emotion regulation (ER) is a core transdiagnostic mechanism implicated in the development and maintenance of anxiety and depression. Although insomnia also plays a key role in these internalizing conditions, it has received comparatively less empirical attention. Moreover, the extent to which insomnia, above and beyond ER, contributes to anxiety and depressive symptoms at different severity levels remains poorly understood. A cross-sectional sample of 2352 adolescents (11-18 years old) completed validated measures assessing ER, insomnia, and symptoms of anxiety and depression. Based on their scores on the Depression, Anxiety and Stress Scales (DASS-21; Lovibond & Lovibond, 1995), participants were classified into four groups: clinical anxiety, subclinical anxiety, clinical depression, and subclinical depression. Within each severity group, hierarchical multiple regression analyses were conducted to determine the unique and incremental contribution of ER and insomnia to anxiety and depressive symptoms, after controlling for age and sex. ER significantly predicted anxiety and depression only within the clinical groups. Insomnia emerged as a significant predictor of anxiety in both subclinical and clinical groups, and of depression in the clinical group, over and above ER and demographic covariates. Across models, insomnia accounted for a greater proportion of explained variance compared to ER. These findings underscore the central role of sleep difficulties and ER as transdiagnostic mechanisms of internalizing psychopathology, particularly at higher symptom levels. They also highlight the importance of prioritizing insomnia-focused interventions, given the robust contribution of sleep disturbances to anxiety and depression across severity groups.