Efficacy of Mobile App–Based Cognitive Behavioral Therapy for Insomnia: Multicenter, Single-Blind Randomized Clinical Trial

Background: Cognitive behavioral therapy for insomnia (CBTi) is the first-line therapy for chronic insomnia. Mobile app–based CBTi (MCBTi) can enhance the accessibility of CBTi treatment; however, few studies have evaluated the effectiveness of MCBTi using a multicenter, randomized controlled trial design. Objective: We aimed to assess the efficacy of Somzz, an MCBTi that provides real-time and tailored feedback to users, through comparison with an active comparator app. Methods: In our multicenter, single-blind randomized controlled trial study, participants were recruited from 3 university hospitals and randomized into a Somzz group and a sleep hygiene education (SHE) group at a 1:1 ratio. The intervention included 6 sessions for 6 weeks, with follow-up visits over a 4-month period. The Somzz group received audiovisual sleep education, guidance on relaxation therapy, and real-time feedback on sleep behavior. The primary outcome was the Insomnia Severity Index score, and secondary outcomes included sleep diary measures and mental health self-reports. We analyzed the outcomes based on the intention-to-treat principle. Results: A total of 98 participants were randomized into the Somzz (n=49, 50%) and SHE (n=49, 50%) groups. Insomnia Severity Index scores for the Somzz group were significantly lower at the postintervention time point (9.0 vs 12.8; t₉₅=3.85; F_2,95=22.76; η_p²=0.13; P<.001) and at the 3-month follow-up visit (11.3 vs 14.7; t₆₈=2.61; F_2,68=5.85; η_p²=0.03; P=.01) compared to those of the SHE group. The Somzz group maintained their treatment effect at the postintervention time point and follow-ups, with a moderate to large effect size (Cohen d=–0.62 to –1.35; P<.01 in all cases). Furthermore, the Somzz group showed better sleep efficiency (t₉₅=–3.32; F_2,91=69.87; η_p²=0.41; P=.001), wake after sleep onset (t₉₅=2.55; F_2,91=51.81; η_p²=0.36; P=.01), satisfaction (t₉₅=–2.05; F_2,91=26.63; η_p²=0.20; P=.04) related to sleep, and mental health outcomes, including depression (t₉₅=2.11; F_2,94=29.64; η_p²=0.21; P=.04) and quality of life (t₉₅=–3.13; F_2,94=54.20; η_p²=0.33; P=.002), compared to the SHE group after the intervention. The attrition rate in the Somzz group was 12% (6/49). Conclusions: Somzz outperformed SHE in improving insomnia, mental health, and quality of life. The MCBTi can be a highly accessible, time-efficient, and effective treatment option for chronic insomnia, with high compliance.