0325 Reducing nocturnal cognitive arousal and rumination mediate treatment effects of digital cognitive behavioral therapy for insomnia

Abstract Introduction High cognitive arousal—i.e., heightened activity often in the form of perseverative thinking—is a central feature insomnia. Emerging evidence from randomized controlled trials (RCTs) support alleviating arousal as mechanism by which behavioral therapy for insomnia (CBTI) reduces symptoms and depression. However, few RCTs have published CBTI data on outcomes. The present study tested whether alleviates symptoms, reducing mediate effects Methods 434 patients with clinical (Insomnia Severity Index [ISI] ≥ 15) were to digital or sleep education control. Study outcomes included (ISI), depression (quick inventory depressive symptomatology self-report 16-item survey, QIDS-SR16), two indices (pre-sleep scale’s factor [PSASC] daytime response scale [DISRS]). Treatment mediation analyses conducted using multivariate linear regression. Results While controlling baseline patients, relative controls, reported lower levels (b=-2.45, p<.001), (b=-1.13, nocturnal (b=-2.37, p<.001) insomnia-focused rumination (b=-3.43, after treatment. Posthoc independent samples t-tests showed that produced small-medium (Cohen’s d=.40) d=.31). Mediation (PSASCT2-T1) mediated 29.0% (αβ=-.709, 95%CI=-1.09, -0.38), 35.1% (αβ=-.397, 95%CI=-0.65, -0.19). (DISRST2-T1) 10.6% (αβ=-.261, 95%CI=-0.50, -0.08), but did not antidepressant (αβ=-.300, 95%CI=-1.46, 0.72). Conclusion Digital effectively alleviated rumination. Moreover, was reduced By comparison, small proportion uninvolved effects. Although facilitated outcomes, is likely limited its modest symptoms. Improving benefits may enhance patient Support (if any) This RCT (NCT03322774) supported NIMH R01-MH122636.