Introduction: Both guided online and individual face-to-face cognitive behavioral therapy for insomnia (CBT-I) are effective in improving insomnia symptoms and sleep efficiency. Little is known about the underlying mechanisms generating this effect. The present study tests the assumption that pre-sleep arousal, sleep-related worry and dysfunctional beliefs about sleep are mediators in the effect of cognitive behavioral treatment for insomnia. Methods: A secondary analysis was performed on data previously collected from a randomized controlled trial (N = 90). In this trial, participants were randomized to either a face-to-face CBT-I condition, an internet-delivered CBT-I condition, or a wait-list group. This article reports on the efficacy of these interventions on pre-sleep arousal, sleep-related worry, and dysfunctional beliefs. Furthermore, we investigated whether these measures mediated the treatment effect on insomnia severity and sleep efficiency. Results: Both treatment modalities were efficacious for these cognitive measures; however, face-to-face treatment showed superiority over the online treatment. All three cognitive measures mediated the effect on insomnia severity. Sleep-related worry and pre-sleep arousal mediated the effect on sleep efficiency, but dysfunctional beliefs did not. Conclusion: Overall, these results point toward the importance of cognitive processes in the treatment of insomnia, implying that psychological treatments for insomnia may best be guided by (also) targeting these cognitive processes.
- Cognitive processes