Effects of a Sound-Based Meditative Intervention on Anxiety, Depression, Salivary Cortisol Levels, and Blood Pressure: A Randomized Controlled Trial

Background Psychological stress contributes significantly to mental and cardiovascular disorders. Chronic activation of stress-response systems has been associated with anxiety, depression, elevated cortisol secretion, autonomic dysregulation, and hypertension. Consequently, complementary and integrative interventions for stress management have received increasing scientific attention. Sound-based meditation has emerged as a promising non-pharmacological approach; however, evidence from randomized controlled trials remains limited. Objective To evaluate the effects of a structured sound-based meditation intervention on anxiety, depression, salivary cortisol levels, and systolic blood pressure compared with a sham sound control condition. Methods A parallel-group randomized controlled trial was conducted among 100 adults aged 21–65 years recruited from meditation centre’s in Tamil Nadu, India. Participants were randomly allocated to either a sound-based meditation intervention group (n = 50) or a sham sound control group (n = 50). Participants assigned to the intervention group attended mandatory in-person group meditation sessions conducted daily for 60 minutes over four weeks. Sessions incorporated recorded sound exposure, including 528 Hz audio, together with acoustic instruments such as singing bowls, bells, gongs, and tingshas. Sessions were conducted under the supervision of three trained meditation instructors and four psychologists. Participants assigned to the control group received a sham sound intervention through a supervised Google Meet platform. Attendance was mandatory, and participants remained visible throughout each session under continuous monitoring by supervisors and psychologists. Psychological outcomes were assessed using the Hospital Anxiety and Depression Scale (HADS). Physiological outcomes included salivary cortisol levels and systolic blood pressure. The primary analysis compared changes between groups from baseline to post-intervention. Results Baseline characteristics did not differ significantly between groups. Compared with the sham control group, participants receiving sound-based meditation demonstrated significantly greater reductions in anxiety, depression, salivary cortisol levels, and systolic blood pressure. Between-group differences in change scores favoured the intervention group for HADS Anxiety (mean difference = −3.30, 95% CI −4.92 to −1.69, p = 0.00010, Cohen's d = 0.81), HADS Depression (mean difference = −1.93, 95% CI −3.53 to −0.33, p = 0.0189, d = 0.48), Salivary Cortisol (mean difference = −2.57 nmol/L, 95% CI −3.23 to −1.91, p < 0.000001, d = 1.54), and Systolic Blood Pressure (mean difference = −7.58 mmHg, 95% CI −10.48 to −4.68, p < 0.000001, d = 1.04). No adverse events were reported.