4 - (OP25) Mechanisms Underlying the Relationship Between Insomnia and Depression: An Exploratory Analysis

Although prior research has consistently demonstrated that insomnia and depression are closely intertwined, the psychological pathways linking these conditions remain unclear. Nearly half of college students experience symptoms of depression, and one in four experiences insomnia, which contributes to functional impairment, academic attrition, suicide risk, and poorer quality of life. To expand upon past research, the present study examined several possible intermediary variables that may serve as transdiagnostic treatment targets.
Participants included college students aged 18-25 (N=80). Each participant answered questions on demographics, depression symptoms, and insomnia. To reduce participant burden, a planned missingness design randomly allocated 50 additional questions to each participant from a larger pool of measures. Additional measures assessed psychological flexibility, emotion regulation, experiential avoidance, sleep-related behaviors, sleep practices and attitudes, and maladaptive personality traits (internalization, detachment, antagonism, disinhibition, anankastia). We tested additional variables as associative variables (AVs), i.e., potential intermediary factors that may account for the insomnia-depression relationship. We analyzed data in R via an exploratory series of analyses to filter appropriate AVs to include in each successive step.
We first assessed zero-order correlations, all candidate pairings of the independent variable (insomnia) and the dependent variable (depression symptoms) were statistically significant (r = .44, p < .001). Next, candidate AVs were entered in step 2 of the hierarchical regression analysis. Results indicated that internalization and detachment, psychological flexibility, sleep-related behaviors, and emotion regulation accounted for increased variability above and beyond insomnia (ΔR² = .12-.26), and proceeded to the final analytic step. Step 3 assessed potential moderating effects of the AVs retained from step 2 on the relationship between insomnia and depression symptoms, none of which emerged as significant moderators. Across analyses, with regard to modifiable transdiagnostic factors, we identified psychological flexibility and emotion regulation as the strongest AVs linking insomnia to depression, with lower levels of each variable predicting greater insomnia severity and depressive symptoms.
These findings begin to clarify processes that may account for the association between insomnia and depression in college students. Integrated treatments addressing both sleep disturbance and these psychological mechanisms may be particularly effective for college students experiencing insomnia or at risk for depression. Prospective testing is needed to determine if changes in these mechanisms temporarily precede, maintain, or increase risk for recurrent depression. Identifying these modifiable psychological processes may strengthen prevention and intervention efforts by informing tools that mitigate the impact of poor sleep and depression, potentially reducing the long-term burden of depression during this critical developmental period.