Digital cognitive behavioral therapy for insomnia for people with comorbid psychological distress: A large scale...

To examine if comorbid anxiety and depression symptoms (psychological distress) moderate intervention effect in participants receiving digital Cognitive Behavioral Therapy for Insomnia (dCBT-I) in a large-scale randomized controlled trial (RCT), compared to a patient education (PE) control condition. Further, we investigate if dCBT-I reduced levels of psychological distress for those with insomnia and comorbid psychological distress.

1721 participants with insomnia completed online assessments of sleep, fatigue and psychological distress, at baseline and at nine-week follow-up. Primary outcome was Insomnia Severity Index (ISI), and secondary outcomes included self-reported sleep (diary), cognition, fatigue, and psychological distress. Participants with psychological distress (HADS>16) were separated from participants without psychological distress. Linear mixed models in SPSS were conducted to test the effects of the intervention.

At nine-week follow-up we found no difference in effect of the intervention between those who had comorbid psychological distress vs. those without psychological distress in terms of insomnia severity (p = 0.552) and fatigue (p = 0.744). Both groups had large effect size improvements on insomnia severity (p < 0.001=), small to medium (Cohen d < 0.08) improvements on fatigue (p < 0.01=) and sleep efficiency (p < 0.001), and small improvement on other sleep diary measures, compared to their respective control group. The psychological distress group showed a small, but statistically significant decrease in psychological distress (d = 0.2, p < 0.05) with dCBT-I compared to PE.

dCBT-I is a viable treatment for Insomnia also for those who have comorbid psychological distress.