The effect of internet-based acceptance and commitment therapy on sleep quality and insomnia in adults: a systematic review and meta-analysis.

Insomnia and poor sleep quality are common sleep-related problems in adults and are associated with impaired quality of life, psychological distress, and increased physical health burden. Although cognitive behavioral therapy for insomnia (CBT-I) is recommended as the first-line non-pharmacological treatment for chronic insomnia, internet-based Acceptance and Commitment Therapy (iACT) has increasingly been explored as an alternative or complementary digital psychological intervention for improving sleep-related outcomes. To systematically evaluate the effects of iACT on sleep quality and insomnia-related outcomes in adults. PubMed, Web of Science, Cochrane Library, CINAHL, and Embase were systematically searched from inception to December 6, 2025. We included randomized controlled trials evaluating internet-based Acceptance and Commitment Therapy in adults that reported validated outcomes for sleep quality or insomnia. Standardized mean differences were pooled using a random-effects model, and risk of bias was assessed using the Cochrane Risk of Bias 2 tool. Eight randomized controlled trials met the inclusion criteria. Five studies were included in the meta-analysis of sleep quality outcomes and three in the meta-analysis of insomnia outcomes. Compared with passive control conditions, iACT was associated with better sleep quality outcomes (SMD = - 0.92, 95% CI - 1.45 to - 0.38; p < 0.001) and reduced insomnia symptoms (SMD = - 0.40, 95% CI - 0.64 to - 0.16; p < 0.001). Exploratory subgroup analyses suggested possible variation in sleep quality outcomes according to intervention duration, participant characteristics, and delivery format, although these findings should be interpreted cautiously. iACT may have potential to improve sleep quality and insomnia-related outcomes in adults. However, the available evidence remains limited by heterogeneous populations, intervention characteristics, delivery formats, and overall low certainty of evidence. Therefore, the findings should be considered preliminary rather than definitive.