Relaxation responses by Tibetan singing bowls

Abstract

Background: There has been significant research interest in traditional singing bowls in recent years. However, the evidence is weak.Objectives: The whole study evaluated the efficacy of the singing bowl sound compared to the yoga exercise control condition in terms of the changes in outcome variables of self-reporting anxiety level and mood, autonomous nervous system adaptability (i.e. pulses and blood pressure) and arousal level (i.e. heart rate variability (HRV))Methods: There were four phases. Firstly the intervention protocol was piloted twice sequentially (study phase I and II). The pilot trials aim to refine the intervention protocol and study design, and estimate the efficacy and effect size which will be used in sample size calculation in the subsequent main study – a randomized cross-over controlled trial.In phase III, a randomised cross-over controlled trial was conducted to rigorously evaluate the efficacy of the singing bow intervention. Yoga exercise was the comparison condition. Participants (n = 47) were randomly assigned to either the intervention or condition groups on a 1:1 ratio. Self-reporting measures included the State-Trait Anxiety Inventory and Profile of Mood States. Physical measures included pulses, blood pressure and heart rate variability measurement. Measuring timepoints were pre-intervention, post-intervention, and 4 weeks after intervention.In phase IV, qualitative process research was conducted, with an aim of gaining in-depth understanding of the participants’ experiences in going through the singing bowl intervention. Past participants (n = 7) with diversified responses were invited to join a focus interview group. Transcription was made with the audio recording. The information was then coded and analysed. Results: Despite small sample sizes in the two pilot trials, findings were positive. At phase I, there were significant drops (p < .05) in heart rate, blood pressure, breathing, anxiety, and negative mood by the Wilcoxon test. There were no significant changes (p > .05) in depression and cortisol. At phase II, there were significant drops (p < .05) in pulses, current-moment anxiety, general perception anxiety, and negative mood. There was no significant change (p > .05) in blood pressure. The positive mood dropped significantly (p < .05). Additionally, the data obtained in the phase II study was used to estimate the sample size for the subsequent Phase III study. At phase III, with the refined intervention protocol, there were significant drops (p < .05) of pulses, at-the-moment anxiety and negative mood in both conditions. Thereappeared to be more amplitudes of drops in the singing bowl. There were no significant changes (p > .05) of blood pressure in both conditions. The general anxiety and heart rate variability were improving in the singing bowl condition only. The positive mood dropped significantly (p < .05) in both conditions. At phase IV, the main themes identified were profound relaxation, selfawareness enhancement, preference of low-pitched sounds, appreciation of detailed debriefing, short-term relaxation and non-positive feelings. Discussion: Phase I and II optimized the research design and logistics for the main study in phase III. In light of the feedback from participants of pilot trials, singing bowl exposure time was prolonged, and measurement tools were shortened. Four singing bowls were utilized. Most results in phases I & II were positive. Similar positive results were obtained in phase III. Counter-intuitively, positive mood was dropping in both phases. A plausible explanation is that in a more mindful state of deep relaxation, positive mood returned to a more neutral level or calm state. The results collected in Phase IV indicated that exposure to the sound enhanced short-term relaxation. Additionally, it appears to induce mindfulness meditation when compared to yoga.Conclusion: Yoga exercise is a well-researched relaxation method, with consistent, strong evidence supporting its efficacy. In comparison to yoga, the traditional singing bowl showed superior relaxation responses in terms of self perceived feelings, mood change and autonomous nervous responses including pulses and heart rate variability.