Efficacy of digital cognitive behavioural therapy for insomnia in Armed Forces and Veteran populations - A systematic review and meta-analysis of randomised controlled trials.

BACKGROUND

Insomnia is highly prevalent in Armed Forces (AF) and veteran populations and undermines readiness and quality of life. While Cognitive Behavioural Therapy for Insomnia (CBT-I) is first-line, access is limited in military settings, and although digital CBT-I offers a scalable alternative, evidence in this population remains limited and not systematically synthesised. The aim of this systematic review and meta-analysis is to evaluate the efficacy of digital CBT-I on insomnia severity in AF personnel.

METHODS

Four electronic databases (PubMed, CENTRAL, Ovid MEDLINE, Ovid PsycINFO, Ovid Embase, Web of Science) were searched between July 12th 2025 to 30th August 2025, supplemented by grey literature searching. Randomised controlled trials (RCT) of AF personnel with insomnia diagnosed via DSM-5 criteria (n = 5) or Insomnia Severity Index (ISI) ≥ 14 (n = 1) were included. Digital CBT-I interventions were compared with minimum contact controls. Participants were included regardless of age, duty status, comorbidities, intervention modality, or setting. Change in ISI scores at post-treatment were meta-analysed using random-effects models, with follow-up assessed descriptively. Risk of bias was assessed using RoB 2, and certainty of evidence was evaluated using GRADE.

RESULTS

Five RCTs (n = 309 intervention; n = 249 control) met inclusion criteria. Pooled post-treatment effects showed a statistically significant moderate-to-large reduction in insomnia severity favouring digital CBT-I, with substantial heterogeneity (I2 = 74%). Leave-one-out sensitivity analyses indicated that this heterogeneity was largely driven by Chao et al.; removal of this study resulted in a considerable reduction in heterogeneity while the overall effect remained robust. Available follow-up ISI scores indicated maintenance of treatment gains up to 12 months. Three studies reported clinically meaningful ISI reductions (≥6 points). Overall risk of bias was unclear or high, primarily due to limited reporting and attrition. Certainty of evidence was rated moderate.

CONCLUSION

Despite limited study numbers, digital CBT-I was shown to be effective in reducing insomnia severity in AF personnel with complex health needs. Future research should address engagement and attrition within digital therapeutics to optimise implementation and treatment efficacy in military settings.