Discussion
fatigue, anxiety, heterogenous insomnia, daytime sleepiness, insomnia, sleep-related, depression, comorbid mental disorder or physical illness
STILL
The present study investigated the effects of digital cognitive behavioral therapy for insomnia (dCBT-I) in comparison to a waitlist control group (WLC). The study setup aimed to recruit a heterogenous insomnia population by setting very limited exclusion criteria. The results of this study showed that low-intensity, digital sleep intervention improved clinical outcomes in addition to usual care in people with insomnia, many of whom suffer with at least one comorbid mental disorder or physical illness. We found large effects of the intervention on insomnia severity and fatigue, and medium-to-large effects on well-being, physical health-related quality of life, symptoms of depression, and anxiety.Improvements during the dCBT-I intervention in sleep continuity and large between-group effects on dysfunctional beliefs about sleep support CBT-I mechanism of action. These findings largely support our hypotheses and are in accordance with previous studies that investigated the effects of dCBT-I on clinical and sleep-related outcomes [Still, a significant number of participants in this trial did not complete all-modules. And although the use of technology may not be equivalent to treatment adherence, it indicates user interest in the intervention. Indeed, a higher dropout rate was observed in module six, when sleep restriction therapy was introduced. An observation that was confirmed by our posttreatment interviews, that a total of 19 participants (16.1%) stated that they had selectively discontinued the sleep restriction therapy module or had subsequently stopped the entire intervention. Furthermore, participants mentioned that modules were forgotten due to a lack of reminders and that it was therefore not possible to complete all-modules in 8-weeks. Although it is possible to set reminders within the application, an automatic reminder function could counteract poor adherence due to forgetting.Despite the fact that the participants’ well-being improved, scores posttreatment were still below the population average [The effects on daytime sleepiness and mental health-related quality of life were smaller in magnitude and absent for domain social relationships as well as for domain environment. While effects on daytime sleepiness are typically expected in the small range [Results of 6- and 12-month follow-up measurements in the intervention group indicated the stability of treatment effects, although small deteriorations were observed for insomnia severity (see Intriguingly, for other measures an inverse pattern was observed (e.g. daytime sleepiness; 8-weeks Despite promising results, a number of limitations need to be mentioned. First, a waitlist control group was used as the choice of comparator, potentially inflating effect sizes on self-reported outcomes due to awareness of group assignment (open-label). Consequently, treatment expectancy may have biased responses in the intervention group and dampened active health behavior in the control group [In this study, we showed that dCBT-I yields improvements beyond insomnia and sleep-related symptoms, enhancing overall well-being and daytime functioning in a heterogenous insomnia population. Results strongly support previous evidence for the use of digital formats to treat insomnia and, due to our limited exclusion criteria, and thus high external validity, allows generalizability to the insomnia population in Germany.