Music therapy and vagally mediated heart rate variability: A systematic review and narrative synthesis.

BACKGROUND: An increasing body of evidence supports the use of music therapy for improving health and wellbeing. In parallel, there has also been a rising interest in the use of biomarkers to assess its impact. One such biomarker is vagally mediated heart rate variability (vmHRV), which is a non-invasive measure of cardiac parasympathetic nervous system activity. However, the influence of music therapy on vmHRV is currently unclear. METHODS: A literature search was performed in December 2023/January 2024 and updated in March 2025. Data related to vmHRV was extracted and risk of bias was evaluated. A narrative synthesis was performed according to the Synthesis Without Meta-analysis (SWiM) guidelines with an effect direction plot. RESULTS: Twenty-eight studies were included. There was large heterogeneity in study samples, contexts, music therapy interventions, and HRV measurement methods. There was also a high risk of bias. The results indicated increased vmHRV during music therapy. There was also an association between improved vmHRV and other positive health outcomes in these studies. DISCUSSION: While current evidence indicates that there are potential positive effects of music therapy on vmHRV, more high-quality research, especially regarding HRV methodology, interpretation and reporting, is needed. A high risk of bias, small sample sizes and heterogeneity in all aspects of the studies prevents any clear conclusions based on the current evidence.