The clinical effects of digital cognitive behavioral therapy for insomnia in a heterogenous study sample: results from a randomized controlled trial

Abstract

Study objectives: Numerous studies worldwide have reported the beneficial effects of digital cognitive behavioral therapy for insomnia (dCBT-I). However, few focus on real-world study samples that reflect people in regular care. To test whether dCBT-I is suitable within German regular care, we designed a randomized controlled trial recruiting a heterogenous insomnia population.

Methods: Participants aged ≥18 who met the criteria for insomnia disorder were randomized to 8-weeks dCBT-I + care-as-usual (CAU) or they were set on a waitlist + CAU. The intervention group was followed-up at 6- and 12-months. The primary outcome was self-reported insomnia severity, assessed with the Insomnia Severity Index (ISI) at 8-weeks post-randomization. A one-way ANCOVA with baseline score as a covariate was fitted to determine group differences. Secondary outcomes included measures of daytime functioning, quality of life, depression, anxiety, dreams, and nightmares.

Results: Of the N = 238 participants (67.6% female), age range 19-81 years, n = 118 were randomized to dCBT-I and n = 120 to the control group. At posttreatment, the use of dCBT-I was associated with a large reduction in the ISI (Diffadj = -7.60) in comparison to WLC (d = -2.08). This clinical improvement was also reflected in responder and remission rates. Treatment effects were also observed for daytime functioning, quality of life, symptoms of depression and anxiety (ds = 0.26-1.02) and at long-term follow-up (intervention group only; ds = 0.18-1.65). No effects were found for dream and nightmare frequency.

Conclusions: This study showed that dCBT-I reduces insomnia symptoms and improves daytime functioning in a heterogenous insomnia population in Germany with sustained long-term treatment effects in the intervention group. Our results underscore the potential of digital health applications, their suitability within regular care, and their role in facilitating widespread implementation of CBT-I as a first-line treatment for insomnia.

Keywords: CBT-I; RCT; cognitive behavioral therapy for insomnia; dCBT-I; digital health; digital therapy; insomnia; randomized controlled trial; regular care; sleep.

Graphical abstract

Figure 1.

Flow chart showing participant selection, dropout, flow, and attrition through the intervention (assessed via self-report).

Figure 2.

Changes in primary outcome and insomnia severity, across both groups and all-assessments. Unadjusted means (±SD) are presented for both groups at baseline and posttreatment, and for the intervention group at 6- and 12-month follow-ups.

Figure 3.

Changes in secondary outcomes: (A) depressive symptoms, (B) anxiety symptoms, (C) Well-being, and (D) Dysfunctional beliefs about sleep, across both groups and all-assessments. Unadjusted means (±SD) are presented for both groups at baseline and posttreatment, and for the intervention group at 6- and 12-month follow-ups.