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

Mind-body practices like meditation are increasingly recognized for their stress-reducing and well-being-enhancing effects. While brain oscillations during meditation have been studied extensively, neuroscientific research on Yogic traditions like Isha Yoga remains limited. This study aims to address this gap by exploring the impact of Isha Yoga practices on brain oscillations and mental well-being. Isha Yoga, a comprehensive system of yoga training, includes various practices such as pranayama (breathwork), breath-watching meditation, and shoonya meditation (a non-dual awareness practice). Pranayama, a preparatory step for meditation, involves controlled breathing and is linked to stress reduction and improved mental clarity. Shoonya meditation, a deconstructive practice aiming to dissolve conceptual distinctions, is less studied neurophysiologically. This study uniquely integrates these three practices within a single investigation, comparing advanced and novice Isha Yoga meditators to meditation-naïve controls. The hypotheses were that different practices would elicit distinct brain oscillatory patterns, advanced meditators would display specific trait effects (greater frontal midline theta power at rest), and both novice and advanced meditators would show a 'relaxed alertness' state during pranayama and breath-watching. Finally, it was hypothesized that meditators would demonstrate better mental health outcomes than controls.

Extensive research demonstrates the positive effects of mind-body practices, especially meditation, on self-awareness, attentional and emotional regulation, and reduction of anxiety and depression symptoms. Electroencephalography (EEG) studies consistently show increased alpha, theta, and gamma power in meditators, indicative of relaxed alertness. Low-frequency oscillations (delta, theta, alpha) generally signify stability and relaxation, while high-frequency oscillations (beta, gamma) are associated with alertness and wakefulness. However, most research focuses on attentional and constructive meditation, with limited studies on deconstructive practices like non-dual meditation. Pranayama, a key component of many Yogic traditions, has also shown benefits but lacks detailed neurophysiological investigation. Studies on Isha Yoga, a specific Yogic tradition, have reported positive cardiovascular, neurophysiological, immune, neurological, and mental health benefits, but more comprehensive EEG studies are needed, particularly integrating pranayama, breath-watching, and shoonya meditation within a single study.

A cross-sectional study was conducted with 103 healthy adults categorized into three groups: advanced meditators (n=42), novice meditators (n=33), and meditation-naïve controls (n=28). Advanced meditators had completed at least one Samyama retreat, while novices had not. Controls had no prior yoga or meditation experience. Participants underwent 128-channel high-density EEG recordings during four sessions: rest (eyes open/closed), sukha kriya pranayama (a gentle alternate nostril breathing practice), breath-watching meditation, and shoonya meditation. A cognitive task was also included, but the results are not discussed in the provided abstract and full text. 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 pre-processed using EEGLAB to remove artifacts. Power spectral analysis was performed for delta, theta, alpha, beta, and gamma frequency bands. Statistical comparisons employed the LIMO toolbox with robust t-statistics and threshold-free cluster enhancement (tfce) for EEG data. For psychometric data, analyses used R packages, including non-parametric tests where assumptions were violated. Multiple comparisons were adjusted using Holm's method.

Resting-state EEG showed significant group differences. Advanced meditators had higher frontal midline theta and lower centro-occipital gamma power than controls. Compared to novices, advanced meditators 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 compared to rest, while controls showed increases only in delta and theta. Breath-watching meditation also elicited increased power across all bands in meditators, but not in controls. Shoonya meditation led to decreased power in novices and controls, but not advanced meditators. Psychometrically, advanced meditators had significantly lower perceived stress and mental distress, and higher well-being and non-attachment than controls and novices. Significant correlations were found between lifetime practice hours and psychometric outcomes. The meditation depth questionnaire indicated significantly greater meditation depth in advanced meditators during both breath-watching and shoonya meditation. Advanced meditators reported higher relaxation, concentration, essential qualities, and non-duality compared to other groups. The Stanford Sleepiness Scale indicated fewer instances of drowsiness post-meditation in meditators compared to controls.

The findings support the hypothesis of distinct neurophysiological effects associated with different Isha Yoga practices and levels of meditation experience. The observed increase in power across frequency bands during pranayama and breath-watching in meditators suggests a state of relaxed alertness, a combination of relaxation (low-frequency power) and alertness (high-frequency power). Advanced meditators exhibited trait-like effects in resting-state EEG, suggesting lasting changes in brain function due to long-term practice. The sustained power across frequency bands during shoonya meditation in advanced meditators, contrasted with the decreased power in novices and controls, points to the unique neural signatures of non-dual awareness practices. The significant improvements in mental health outcomes in meditators may result from enhanced meta-awareness, cognitive flexibility (dereification), and relaxed alertness. The study's results align with the phenomenological matrix model of meditation.

This study demonstrates that Isha Yoga practices produce distinct neurophysiological and psychological effects depending on meditation proficiency. Advanced meditators show trait changes, while both novice and advanced meditators exhibit a state of relaxed alertness. Advanced meditators report experiencing non-duality during breath-watching and shoonya meditation, with associated EEG differences. Proficiency in Isha Yoga is linked to better mental health outcomes. Future research should address limitations like the cross-sectional nature of the study and incorporate neurophenomenological approaches to explore subjective experiences during various practices.

The cross-sectional design limits causal inference. The inability to control the session order and potential fatigue introduced by longer sessions could also influence the results. Contextual factors, personality traits, and motivation were not investigated comprehensively. A neurophenomenological study would be valuable for better understanding the subjective experiences during meditation.