Effects of a Sound-Based Meditative Intervention on Anxiety, Depression, Salivary Cortisol Levels, and Blood Pressure: A Randomized Controlled Trial
Description
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.
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The study consisted of a convenience sample of 100 participants, with ages ranging from 21- 65 years; the mean age = 46.37 years, SD = 13.50 years, 50 females (n=50) and 50 males (n=50). Sound-based meditation was conducted at the Meditation Centres of the UNS Research Council, Tamil Nadu, India. This randomised controlled study was performed over approximately four weeks from mid-November 2024–mid-December 2024. The participants were provided with standardised questionnaires before meditation, which included the Hospital Anxiety and Depression Scale (HADS) (Snaith). Tension, anger and stress are analysed via the Profile of Mood States (POMS-SF) (Shacham)to assess well-being. Blood pressure was monitored via automated sphygmomanometers (O'Brien E) regularly before and after sound-based meditation. Additionally, the morning blood cortisol level (J Aubets) was evaluated before the commencement of the trial and four weeks after the completion of sound-based meditation. Following meditation, the participants were also asked about the questionnaires with post meditation questionnaires to evaluate the significance of the trial. The data were collected by the principal investigator Mr. Suresh Sathyanarayanan. Dr Hemachandran Ravikumar, MRSB. Rsci (UK) drafted the reports and generated the scientific findings. All the participants provided written concerns about volunteering in the study, and the study was approved by the Institutional Review Board (IRB) & Institutional Ethics Committee (IEC) of the UNS Research Council. The participants are randomly divided into two groups. The control group (n=50) comprises 50 participants who undergo meditation without the intervention of sound frequencies (placebo), and the other group is an experimental group (n=50) comprising 50 participants who undergo sound-based meditation (Intervention). The participants were advised to bring yoga mats or blankets to perform sound-based meditation (Goldsby). They can choose their comfortable position. The participants can also lie down in a supine position to synchronise easily with the process. The participants in the control group and the experimental group were evaluated separately. The control group (n=50) and experimental group (n=50) are numbered with participant IDs for easy evaluation. The participants are arranged in circular form so that the sound-producing instruments and prerecorded sound frequency can be played from the centre. then the experimental group will experience sound-based meditation for 60 minutes. the participants are given the pre and post-meditation questioneries form The analysis was performed with SciPy 1.0, Microsoft Excel 2007, and D. (2007),
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Funders
- UNS Research CouncilGrant ID: UNS/FEQ/2024