Abstract
STUDY OBJECTIVES: Insomnia is associated with elevated levels of suicidal thoughts and behaviors. Emerging evidence suggests that cognitive-behavioral therapy for insomnia (CBTI) may reduce suicidal ideation (SI). However, the role of digital therapeutics in both the alleviation and prevention of SI remains unclear, and treatment mechanisms facilitating SI reductions have not been clearly identified. METHODS: A total of 658 adults with Diagnostic and Statistical Manual of Mental Disorders, 5th Edition insomnia disorder enrolled in a single-site randomized controlled trial evaluating the efficacy of digital CBTI relative to attention control. Outcomes were measured at pretreatment, posttreatment, and 1-year follow-up. RESULTS: Before treatment, 126 patients endorsed SI (19.1% prevalence). Among those with baseline SI, CBTI patients reported lower SI rates at posttreatment (30.0% vs 54.5%, p = .005) and 1-year follow-up (29.6% vs 46.8%, p = .042) relative to control. PRODCLIN analysis estimated that half of suicidolytic effects of CBTI were mediated through insomnia remission. Among those without baseline SI, CBTI did not directly prevent new onset SI. However, insomnia remitters reported lower rates of new-onset SI at posttreatment relative to non-remitters (1.5% vs 6.5%, p = .009). Mediation analysis supported a significant indirect effect wherein CBTI increased the likelihood of insomnia remission, which was associated with SI prevention (αβ = -3.20, 95% CI = -5.74 to -0.87). CONCLUSION: Digital CBTI reduces insomnia symptoms, which promotes SI alleviation and prevention. For nonsuicidal patients, digital CBTI may serve as a highly accessible monotherapy for improving sleep, thereby reducing the risk for SI. For suicidal patients, digital CBTI may be appropriately administered as an adjunct treatment to support mainline intervention more directly targeting suicidogenic thoughts.