Raga Bhairavi in virtual reality reduces stress-related psychophysiological markers

The effects of classical music on psychophysiological parameters are not well understood. This study aimed to investigate the impact of listening to raga Bhairavi, an Indian Classical Music for six days on anxiety, stress, depression, and heart rate variability (HRV) parameters. Forty-four individuals were randomly assigned to either the intervention group (VR-raga), where they listened to raga Bhairavi via 360° video in a virtual reality environment, or the control group, where there was no exposure to raga Bhairavi for six days. Before allocation, the HRV baselines (relax-baseline and stress-baseline) were recorded on the first day. On the first and sixth days of the intervention, HRV was monitored, and the Depression, Anxiety, and Stress Scale (DASS-21) questionnaire was administered before and after the intervention. After six days, all DASS-21 subscales were significantly reduced in the VR-raga group. A similar trend was observed in the seven HRV parameters evaluated in this study, which demonstrated reduced physiological stress and enhanced autonomic balance following the six-day intervention. The findings collectively indicated the efficacy of the VR-based raga Bhairavi intervention in reducing psychological stress markers and highlighted the potential applications of utilizing the VR-based raga intervention for improving mental well-being in the real-world context.

A comprehensive evaluation of linear and non-linear HRV parameters between paced breathing and stressful mental state

Background

Heart rate variability (HRV) is a crucial metric that provides valuable insight into the balance between relaxation and stress. Previous research has shown that most HRV parameters improve during periods of mental relaxation, while decreasing during tasks involving cognitive workload. Although a comprehensive analysis of both linear and non-linear HRV parameters has been carried out in existing literature, there still exists a need for further research in this area. Additionally, limited knowledge exists regarding how specific interventions may influence the interpretation of these parameters and how the different parameters correlate under different interventions. This study aims to address these gaps by conducting a thorough comparison of different linear and non-linear HRV parameters under mentally relaxed versus stressful states.

Methodology

Participants were randomly and equally divided among two between-subjects groups: relaxed-stress (RS) (N = 22) and stress-relaxed (SR) (N = 22). In the RS group, a paced breathing task was given for 5 min to create relaxation, and was followed by a 5-min time-based mental calculation task to create stress. In the SR group, the order of the stress and relaxed tasks was reversed. There was a washout period of 15 min after the first task in both groups.

Results

Of the 37 HRV parameters, 33 differed significantly between the two interventions. The majority of the parameters exhibited an improving and degrading tendency of HRV parameters in the relaxed and stressed states, respectively. The correlation of the majority of HRV parameters decreases during stress, while prominent time domain and geometric domain parameters stand out in the correlation.

Conclusion

Overall, HRV parameters can be reliably used to assess a person's relaxed and stressed mental states during paced breathing and mental arithmetic task respectively. Furthermore, non-linear HRV parameters provide accurate estimators of the mental state, in addition to the commonly used linear parameters.