Supplementary Material for: The Effects of Digital Cognitive Behavioral Therapy for Insomnia in Chronic Pain: A Randomized Controlled Trial

Introduction. Managing chronic pain is a significant healthcare challenge requiring a multimodal approach. The frequent presence of comorbid insomnia and its bidirectional relationship with pain complicates treatment. This study tested whether adding digital cognitive behavioral therapy for insomnia (dCBT-I) to standard chronic pain treatment improves symptoms compared to a waitlist control (WLC).

Methods. Participants with chronic pain and insomnia were randomized (1:1) to dCBT-I or WLC. Assessments occurred at baseline, eight, and 24 weeks post-randomization. The primary outcome was insomnia severity (Insomnia Severity Index; ISI). Secondary outcomes included sleep- and pain-related symptoms, well-being, and dreams. Linear mixed models assessed between-group differences.

Results. A total of 207 participants (182 women, mean age=51.96±12.97 years) were randomized to dCBT-I (n=103) or WLC (n=104). The dCBT-I group showed large improvements in insomnia severity versus WLC at both eight (-4.36, p<.001; d=-1.18) and 24 weeks (-4.88, p<.001; d=-1.32). Pain-related impairments and life control also improved, favoring dCBT-I (ds=0.22–0.35). Moderate-to-large effects were observed for secondary outcomes, including daytime sleepiness, fatigue, and dysfunctional sleep beliefs (ds=0.47-1.12).

Conclusion. dCBT-I effectively reduces insomnia severity in individuals with chronic pain and insomnia. Improvements in chronic pain symptoms highlight its potential as a scalable, evidence-based intervention for multimodal pain management.