Effects of a Sound-Based Meditative Intervention on Anxiety, Depression, Salivary Cortisol Levels, and Blood...

Background Psychological stress contributes to mental health symptoms and cardiovascular risk through pathways involving anxiety, depression, cortisol secretion, autonomic dysregulation, and elevated blood pressure. Sound-based meditation is a nonpharmacological approach that may support stress management, but randomized controlled trial evidence remains limited. Objective The objective was to evaluate whether a structured sound-based meditation intervention was associated with lower post-intervention anxiety symptoms, measured using the Hospital Anxiety and Depression Scale-Anxiety subscale (HADS-A), than a remotely delivered music-control condition after four weeks. Depressive symptoms, salivary cortisol concentration, systolic blood pressure, and exploratory diastolic blood pressure were also assessed. Methodology This parallel-group randomized controlled trial enrolled 100 adults aged 21-65 years from meditation centers and surrounding communities in Tamil Nadu, India. Participants were randomly assigned in a 1:1 ratio to a sound-based meditation intervention group (n = 50) or a remotely delivered music-control group (n = 50). The intervention group attended supervised, face-to-face, 60-minute daily sound-based meditation sessions for four weeks, involving recorded 528-Hz audio and acoustic instruments, including singing bowls, gongs, bells, and tingshas. The control group attended supervised 60-minute Google Meet sessions using two standardized, licensed music tracks with scheduled silent intervals. The primary analysis used analysis of covariance (ANCOVA) to compare post-intervention HADS-A scores between groups, adjusted for baseline HADS-A scores. Corresponding ANCOVA models evaluated HADS-D, salivary cortisol, and systolic blood pressure as secondary outcomes; diastolic blood pressure was exploratory. Holm adjustment was applied across the five reported outcomes. Results  Observed baseline characteristics were comparable between groups. In baseline-adjusted ANCOVA analyses, post-intervention HADS-A scores were lower in the intervention group than in the music-control group (adjusted mean difference = -2.55, 95% confidence interval (CI): -3.62 to -1.48; Holm-adjusted P < 0.001; partial η ² = 0.19). Corresponding adjusted differences favored the intervention group for HADS-D (adjusted mean difference = -2.39, 95% CI: -3.36 to -1.43; Holm-adjusted P < 0.001; partial η ² = 0.20), salivary cortisol (-2.54 nmol/L, 95% CI: -2.95 to -2.13; Holm-adjusted P < 0.001; partial η ² = 0.61), systolic blood pressure (-7.62 mmHg, 95% CI: -9.36 to -5.89; Holm-adjusted P < 0.001; partial η ² = 0.44), and exploratory diastolic blood pressure (-2.22 mmHg, 95% CI: -3.00 to -1.43; Holm-adjusted P < 0.001; partial η ² = 0.24). No adverse events were reported. Conclusions This randomized controlled trial provides preliminary evidence that participation in a structured sound-based meditation program was associated with greater short-term improvements in anxiety, depression, salivary cortisol, systolic blood pressure, and exploratory diastolic blood pressure compared with a remotely delivered music-control condition. These findings should be confirmed in larger, fully standardized randomized controlled trials with longer follow-up and diverse populations.