Relaxed Alertness in Novice and Advanced Meditators – A Neurophysiological and Psychological Study of Isha Yoga Practices

Mind-body practices like meditation are increasingly popular for stress reduction and well-being enhancement. While numerous studies explore brain oscillations during meditation, research on Yogic traditions, particularly Isha Yoga, remains limited. This study addresses this gap by investigating the impact of Isha Yoga practices—sukha kriya pranayama (alternate nostril breathing), breath-watching, and shoonya meditation (non-dual awareness)—on brain oscillations and mental well-being. The study hypothesizes differential brain oscillatory dynamics, greater power during attentional practices (pranayama and breath-watching), greater frontal midline theta power in advanced meditators at rest, and a state of relaxed alertness during pranayama and breath-watching in both novice and advanced meditators. Furthermore, it predicts better mental health outcomes and deeper states of consciousness in advanced meditators. The study's significance lies in understanding the neurophysiological mechanisms underlying Isha Yoga and providing evidence-based support for its potential benefits in addressing rising mental health challenges.

Existing research extensively documents the benefits of meditation, highlighting its ability to establish a state of relaxed alertness characterized by increased alpha, theta, and gamma brainwave activity. Low-frequency oscillations (delta, theta, alpha) often indicate stability and relaxation, while high-frequency oscillations (beta, gamma) are associated with alertness and wakefulness. However, most studies focus on attentional and constructive meditation, with fewer investigating deconstructive practices like non-dual meditation. Pranayama, a preparatory step for meditation in Yogic traditions, is shown to calm the mind and improve mental clarity, with a growing body of evidence supporting its positive effects on physical and mental health. Studies on Isha Yoga have reported various benefits, including cardiovascular, neurophysiological, immune system, neurological, and mental health improvements. While Shambhavi Mahamudra Kriya, Shoonya, and Samyama are integral parts of Isha Yoga, neurophysiological studies on these practices, particularly Shoonya, are limited. This study aims to address this research gap by integrating EEG data into the phenomenological matrix model of meditation to provide a comprehensive understanding of these practices.

This cross-sectional study recruited 103 healthy adults categorized into three groups: 42 advanced meditators (ADV), 33 novice meditators (NOV), and 28 meditation-naïve controls (CNT). Advanced meditators had completed at least one Samyama retreat, while novices had not. Controls had no prior meditation experience. Participants underwent high-density (128-channel) EEG recordings during four sessions: Rest1, sukha kriya pranayama, breath-watching, Rest2 (with meditation depth questionnaire), cognitive task, Rest3, shoonya meditation, and Rest4 (with meditation depth questionnaire). The Geodesic EEG System 300 was used, with data pre-processed using EEGLAB. Psychometric assessments included the Perceived Stress Scale (PSS), PHQ-4 (anxiety and depression), WHO Well-being Index (WHO-WBI), Non-attachment Scale (NAS-7), Meditation Depth Questionnaire (MEDEQ), and Stanford Sleepiness Scale (SSS). EEG data were analyzed using the LIMO toolbox, with robust t-statistics and multiple comparisons corrected using cluster statistics. Psychometric data were analyzed using RStudio with appropriate parametric or non-parametric tests. Effect sizes and correlations were calculated.

Resting-state EEG revealed significant group differences. Advanced meditators showed higher frontal midline theta and lower centro-occipital gamma power compared to controls. Compared to novices, they exhibited globally heightened theta and alpha power and increased fronto-midline and central beta power. During pranayama, meditators showed increased power across all frequency bands, while controls showed increases only in delta and theta. Breath-watching showed similar increases in low- and high-frequency bands in meditators, but not in controls. Shoonya meditation resulted in reduced power in novices and controls, but sustained power in advanced meditators. Psychometrically, advanced meditators showed significantly lower perceived stress and mental distress, and higher well-being and non-attachment compared to other groups. Significant positive correlations were found between lifetime practice hours and well-being, non-attachment, and negative correlations with stress and mental distress. Meditation depth questionnaires revealed significantly greater depth in advanced meditators during breath-watching and shoonya, correlating positively with lifetime practice hours. The Stanford Sleepiness Scale showed a greater percentage of controls experiencing drowsiness compared to meditators, particularly during breath-watching.

The findings support the hypothesis that Isha Yoga practices elicit distinct state and trait changes at both neural and psychological levels. The observed relaxed alertness in meditators is consistent with previous research, showing a unique combination of increased low- and high-frequency power. The sustained power in advanced meditators during shoonya suggests a stable state of stillness, potentially linked to non-dual awareness. The correlation between lifetime practice hours and mental health outcomes underscores the long-term benefits of Isha Yoga. The integration of EEG and psychometric data into the phenomenological matrix model provides a framework for understanding the subjective experiences during these practices. The greater meditation depth and non-duality reported by advanced meditators align with neuroscientific findings of higher theta, alpha, and beta power.

This study demonstrates the distinct neurophysiological and psychological effects of Isha Yoga practices, particularly on experienced practitioners. The findings highlight the state of relaxed alertness and improved mental well-being associated with these practices. Future research should explore the causal relationship between practice and outcomes, investigate individual differences, and incorporate neurophenomenological approaches to deepen understanding of subjective experiences. Mind-body practices like Isha Yoga offer significant potential benefits for mental health.

The cross-sectional design limits causal inferences. The inability to control session order might have introduced order effects. Potential fatigue due to session length, especially in controls, might have influenced results. Lack of investigation into individual differences and contextual factors could affect the generalizability of findings. The absence of neurophenomenological data also limits the understanding of subjective meditative experiences. Future longitudinal studies with larger samples and the incorporation of neurophenomenological methods are needed to further investigate these practices.