Objective:

To evaluate the independent effects of standalone digital mindfulness-based interventions (DMBIs) on sleep and mental health outcomes in adults, addressing the gap in existing research.

Key Findings:

• Standalone DMBIs significantly improved sleep health with a moderate effect size (Hedges’ g = 0.38, p < 0.001; very low-certainty evidence).
• DMBIs also improved mental health with a moderate effect size (Hedges’ g = 0.33, p < 0.01; very low-certainty evidence).
• High heterogeneity and publication bias reduced the certainty of evidence to very low levels, impacting the reliability of the findings.

Interpretation:

The findings support the potential of standalone DMBIs as a scalable and cost-effective approach to improve sleep and mental health, highlighting the need for further high-quality research to validate these results.

Limitations:

• High heterogeneity among studies, which may affect the generalizability of the findings.
• Publication bias affecting evidence certainty, potentially skewing results.
• Very low-certainty evidence due to methodological limitations, necessitating cautious interpretation.

Conclusion:

Standalone DMBIs may be effective in improving sleep and mental health, but further research is essential to enhance evidence quality and optimize intervention strategies, particularly addressing the identified limitations.