Feasibility and Preliminary Effectiveness of a Prototype Digital Therapeutic for Insomnia (LUIT-K): A Pilot Study

Objective: Insomnia is a prevalent and burdensome condition, with limited access to evidence-based treatments like cognitive behavioral therapy for insomnia (CBT-I). Digital therapeutics offer a promising solution to bridge this treatment gap, necessitating early-phase evaluations for usability and clinical effectiveness. This pilot study aimed to evaluate the feasibility, preliminary effectiveness, and user experience of LUIT-K, a prototype mobile-based digital therapeutic delivering CBT-I content, in a Korean adult population with insomnia symptoms.Methods: Ten adults experiencing insomnia symptoms (Insomnia Severity Index [ISI] ≥8) completed a 6-week single-arm intervention using the LUIT-K mobile app. Validated self-report measures were administered at baseline and endpoint, including the ISI, Pittsburgh Sleep Quality Index-Korean version (PSQI-K), Korean Epworth Sleepiness Scale (KESS), Patient Health Questionnaire-9 (PHQ-9), Generalized Anxiety Disorder-7 (GAD-7), Dysfunctional Beliefs about Sleep (DBAS), Sleep Hygiene Practices Scale (SHPS), and Korean version of the Biological Rhythms Interview of Assessment in Neuropsychiatry (K-BRIAN). Usability and user experience were assessed using an 11-item structured survey and open-ended feedback. Responder analysis was conducted based on a ≥6-point improvement in ISI scores.Results: Significant reductions were observed in ISI scores, decreasing from a mean of 16.7 (SD=5.1) at baseline to 11.9 (SD=5.0) at endpoint (p=0.04). This change indicates a modest clinical improvement at the group level; at the individual level, 40% of participants were classified as responders based on the ISI criterion of a 6-point reduction. Additionally, statistically significant improvements were noted in PSQI-K (p=0.02) and SHPS (p=0.01) scores, with a trend toward improvement in KESS (p=0.06) but no significant change in DBAS (p=0.38) and GAD-7 (p=0.48). Qualitative feedback highlighted technical issues and usability as the most frequent complaints.Conclusion: This pilot study provides preliminary support for the feasibility and clinical potential of the LUIT-K digital CBT-I app. Findings suggest that early symptom improvement is associated with a more favorable user experience, underscoring the importance of iterative design informed by both clinical and user-centered data. Further large-scale controlled studies are warranted to confirm efficacy and optimize deployment strategies.