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

The study investigates how specific Isha Yoga practices influence neurophysiological brain oscillations and psychological outcomes in individuals with varying meditation expertise. Mind–body practices like pranayama and meditation are linked to improved attention, emotion regulation, and well-being, yet neuroscientific work on Yogic traditions—especially pranayama and deconstructive, non-dual practices such as Shoonya—is limited. The authors aimed to: (1) characterize EEG oscillatory changes during sukha kriya pranayama (alternate-nostril breathing), breath-watching, and Shoonya meditation; (2) assess state versus trait effects across advanced meditators, novice meditators, and meditation-naïve controls, hypothesizing increased power across low- and high-frequency bands (relaxed alertness) during attentional practices and elevated frontal midline theta traits in advanced meditators; and (3) compare psychometric outcomes (perceived stress, mental distress, non-attachment, and well-being) and meditation depth, hypothesizing better mental health outcomes and deeper states among advanced meditators.

Prior EEG research on meditation commonly reports increased alpha, theta, and gamma power associated with relaxed alertness and enhanced attentional control. Low-frequency oscillations (delta, theta, alpha) relate to stability/relaxation, while higher frequencies (beta, gamma) reflect alertness and perceptual clarity. There is a paucity of EEG studies on pranayama and deconstructive practices (e.g., non-dual awareness). Isha Yoga practices (e.g., Shambhavi Mahamudra Kriya, Shoonya, Samyama) have been associated with cardiovascular, neurophysiological, immune, neurological, and mental health benefits in prior studies. Breath-watching in Isha Yoga resembles mindfulness of breathing but is embedded within a broader practice sequence. Shoonya is a non-dual awareness meditation emphasizing conscious non-doing; advanced practitioners across traditions report minimal phenomenal experiences characterized by reduced self–other boundaries. The phenomenological matrix model (Lutz et al., 2015) offers a framework to integrate attentional, constructive, and deconstructive practices by dimensions such as object orientation, dereification, and meta-awareness.

Design: Cross-sectional study comparing three groups: advanced Isha meditators (ADV; n=42), novice Isha meditators (NOV; n=33), and meditation-naïve controls (CNT; n=28).

Participants: Healthy adults recruited in Karnataka, India. Advanced meditators had completed at least one Samyama retreat; novices had not. Controls had no prior yoga/meditation exposure. Advanced: mean age 35.57 (SD 6.81), mean lifetime Isha practice ≈ 5507.8 h (SD 2897.44). Novice: mean age 31.66 (SD 7.64), mean lifetime practice ≈ 1637.24 h (SD 1126.61). Controls: mean age 31.14 (SD 6.38). Groups matched for age, education, marital and socioeconomic status. Inclusion/exclusion criteria detailed in Supplementary Tables. Ethics approval obtained (NIMH/DO/ETHICS SUB-COMMITTEE MEETING/2018); informed consent obtained.

Procedure: EEG recorded continuously across four sessions in fixed order: (1) sukha kriya pranayama (6 min), (2) breath-watching (15 min), (3) cognitive task (visual oddball; not reported here), and (4) Shoonya meditation (15 min). Each session had pre- and post- 4-min rest blocks alternating 1-min eyes-closed/open. A washout followed Rest2 before the cognitive task; Meditation Depth Questionnaire (MEDEQ) was administered after Rest2 (post breath-watching) and after Rest4 (post Shoonya). Meditators performed their standard practices; controls were given analogous instructions (alternate-nostril breathing, breath-watching, and sit-still with Shoonya-like instructions). Order was not counterbalanced due to traditional sequencing.

EEG acquisition and preprocessing: 128-channel HydroCel nets (Philips Neuro GES 300), NetAmps300 amplifier, 24-bit, DC, 1 kHz sampling; Cz reference, AFz ground. Recordings in a dim, sound-attenuated chamber at 25°C, 40–60% humidity, stimuli presented with E-Prime 2.0. Preprocessing with EEGLAB v2021.0 (MATLAB R2021b): resampled to 250 Hz; average reference; high-pass 0.5 Hz, low-pass 80 Hz, 50 Hz notch. Artifact Subspace Reconstruction (ASR; 5 SD) removed bad channels/segments. ICA (infomax) and ICALABEL (90% threshold) removed ocular, muscle, ECG components. Spherical spline interpolation of channels. Mean % data removed (Min–Max): ADV 11.19% (1.33–45.16), NOV 12.61% (1.3–66.7), CNT 11.21% (0.38–57.17). Mean ICs removed: ADV 3.14 (0–21), NOV 2.41 (0–21), CNT 3.99 (0–25).

EEG spectral analysis: Band-power from 2 s epochs (0.5 Hz resolution; Hamming window) for delta (1–4 Hz), theta (4–8 Hz), alpha (8–12 Hz), beta (13–30 Hz), gamma (30–80 Hz). Statistical testing used LIMO toolbox robust t-statistics with 2000 permutations; multiple comparisons corrected via threshold-free cluster enhancement (TFCE) controlling FWER; alpha < 0.05.

Psychometric measures: Perceived Stress Scale (PSS-10); PHQ-4 for anxiety/depression (total and subscales); WHO-5 Well-Being Index; Non-Attachment Scale (NAS-7); Meditation Depth Questionnaire (MEDEQ; total and five clusters: hindrances, relaxation, concentration, essential qualities, non-duality); Stanford Sleepiness Scale (SSS; dichotomized into Alert vs Not Alert). Internal consistencies were acceptable to excellent as reported.

Psychometric analyses: RStudio (v1.4.1106). For non-normal data, Kruskal–Wallis with Dunn pairwise tests; for normal data, Welch’s ANOVA with Games–Howell pairwise tests. Holm correction for multiple comparisons. Effect sizes with 95% CIs. Pearson correlations for continuous associations. Significance p < 0.05. APA reporting via ggstatsplot.

Resting-state trait effects (eyes-closed baseline, RC1):

• Advanced vs Controls: Advanced meditators had higher frontal midline theta power and lower gamma power in centro-occipital regions.
• Advanced vs Novice: Advanced showed globally heightened theta and alpha power, and increased beta power in fronto-midline/central regions.
• Novice vs Controls: Novices showed lower alpha power in left posterior regions and lower gamma power in localized centro-occipital regions. Baseline differences were more pronounced between advanced and novice than between advanced and controls.

Pranayama (PY) vs Rest (RC1), within-group:

• Controls: Increased delta (anterior) and frontal midline theta; no major changes in alpha/beta/gamma.
• Novice and Advanced meditators: Increased power across all frequency bands; novices showed global increases; advanced showed more localized increases. Between-group during pranayama:
• Novice vs Controls: Novices had greater theta power in posterior regions, greater beta power in frontal/central regions, and greater gamma power in frontal, central, and occipital regions.
• Advanced vs Controls: Advanced showed greater gamma power in some frontal and occipital regions.
• Advanced vs Novice: No major differences; trend toward higher power in novices. Overall, pranayama induced widespread increases across bands in meditators, consistent with relaxed alertness, whereas controls mainly increased low-frequency power.

Breath-watching (BW) vs Rest (RC1), within-group:

• Controls: Increased delta and theta (anterior), decreased alpha (occipital), no major beta/gamma changes.
• Novice and Advanced meditators: Significant global increases in delta, theta, and beta; no major changes in alpha or gamma. Between-group during breath-watching: No significant group differences; trends toward higher alpha/beta/gamma in meditators relative to controls.

Shoonya (SS) vs Rest (RC3), within-group:

• Advanced meditators: No significant differences between rest and Shoonya (power sustained across bands).
• Novice meditators: Global reduction in power, particularly delta, beta, and gamma.
• Controls: Global decrease across all bands. Between-group during Shoonya:
• Advanced vs Controls: Advanced exhibited significantly greater power globally across all frequency bands.
• Advanced vs Novice: Advanced showed significantly greater power globally across all bands except delta.
• Novice vs Controls: Novices showed greater power in all bands, but only in limited regions. Post- vs Pre-Shoonya rest: Advanced showed no significant differences; novices had localized reductions across bands; controls had widespread decreases.

Psychometric outcomes (group differences):

• Perceived Stress: Kruskal–Wallis χ² = 12.39, p < 0.001, η²ordinal = 0.12; pairwise: ADV < CNT (PHolm < 0.001).
• WHO Well-Being: χ² = 20.33, p < 0.001, η²ordinal = 0.20; pairwise: ADV > CNT (PHolm < 0.001), ADV > NOV (PHolm < 0.05), NOV > CNT (PHolm < 0.05).
• Non-attachment (NAS-7): χ² = 18.42, p < 0.001, η²ordinal = 0.18; pairwise: ADV > CNT (PHolm < 0.001), NOV > CNT (PHolm < 0.001).
• Mental Distress (PHQ-4 total): χ² = 18.09, p < 0.001, η²ordinal = 0.18; pairwise: ADV < CNT (PHolm < 0.001), NOV < CNT (PHolm < 0.05). Medians: PSS (CNT 18; NOV 13; ADV 12); WHO-5 (CNT 64; NOV 76; ADV 80); NAS-7 (CNT 33; NOV 37; ADV 39); PHQ-4 (CNT 3; NOV 1; ADV 0).

Correlations with lifetime Isha practice hours (n=103):

• Perceived Stress: r = –0.36, t(101) = –3.84, p < 0.001.
• Mental Distress (PHQ-4): r = –0.35, t(101) = –3.71, p < 0.001.
• WHO Well-Being: r = 0.36, t(101) = 3.85, p < 0.001.
• Non-attachment: r = 0.35, t(101) = 3.76, p < 0.001.

Meditation Depth Questionnaire (MEDEQ):

• Breath-watching depth: Welch’s F(2,44.17) = 20.59, p < 0.001, ω² = 0.45; ADV > CNT (PHolm < 0.001), ADV > NOV (PHolm < 0.05), NOV > CNT (PHolm < 0.001). Correlation with lifetime hours: r = 0.47, t(68) = 4.37, p < 0.001.
• Shoonya depth: Welch’s F(2,39.75) = 26.98, p < 0.001, ω² = 0.55; ADV > CNT (PHolm < 0.001), ADV > NOV (PHolm < 0.05), NOV > CNT (PHolm < 0.001). Correlation with lifetime hours: r = 0.51, t(64) = 4.70, p < 0.001. Subscales: Advanced showed lower hindrances and higher relaxation, concentration, essential qualities, and non-duality vs others; novices exceeded controls on several subscales.

Stanford Sleepiness Scale (alertness proportions):

• Before breath-watching: ADV 95%, NOV 84%, CNT 80% alert. After: ADV 78%, NOV 72%, CNT 52% alert.
• Before Shoonya (or sit-still for controls): ADV 81%, NOV 90%, CNT 92% alert. After: ADV 97%, NOV 93%, CNT 62% alert.

Overall: Meditators (especially advanced) exhibited neural signatures of relaxed alertness during pranayama and breath-watching, sustained power during Shoonya in advanced meditators, deeper meditation states (including non-duality), and better mental health indicators vs controls.

Findings support that Isha Yoga practices engender a state of relaxed alertness, characterized by concurrent increases in low-frequency (delta, theta, alpha) indices of stability/relaxation and higher-frequency (beta, gamma) indices of alertness and perceptual clarity during attentional practices (pranayama, breath-watching). Advanced meditators exhibit trait differences at rest (elevated frontal midline theta and broader low-frequency power), suggesting enduring neurophysiological adaptations. During pranayama, controls increased mainly low-frequency power (relaxation), whereas meditators also increased beta/gamma (wakeful clarity), implying that expertise facilitates the full relaxed-alert state. Breath-watching similarly showed global increases in delta/theta/beta in meditators, while controls showed signs consistent with drowsiness (theta increase and alpha decrease). Shoonya, a deconstructive non-dual practice, differentiated groups: advanced meditators maintained stable power from rest through Shoonya and post-Shoonya, consistent with a sustained stillness trait and phenomenology of non-duality; novices and controls showed power reductions, possibly reflecting reduced network synchronization and increased hindrances or drowsiness. Psychometric results converge with EEG: meditators reported fewer hindrances, greater relaxation and concentration, greater non-duality, and better mental health. The positive associations between lifetime practice and well-being, non-attachment, and meditation depth further reinforce practice-dependent benefits. Mapping results to the phenomenological matrix indicates enhanced meta-awareness, dereification, clarity, and stability in experienced practitioners, especially during breath-watching and Shoonya.

Isha Yoga practices yield distinct neurophysiological and psychological effects that vary with meditation expertise. Advanced meditators display trait EEG differences at rest and sustain power during Shoonya, consistent with non-dual awareness states. Both novice and advanced meditators achieve relaxed alertness during pranayama and breath-watching, whereas controls mainly show low-frequency increases and more drowsiness. Meditators also report greater meditation depth and better mental health (lower stress and distress; higher well-being and non-attachment), with benefits correlating with lifetime practice hours. These findings elucidate unique brain signatures of Yogic mind–body practices and highlight their potential for enhancing mental health and well-being. Future research should employ longitudinal and neurophenomenological designs, include experiential sampling, and further dissect mechanisms and dose–response relationships across diverse Yogic practices.

• Cross-sectional design limits causal inference.
• Fixed practice order (per traditional sequencing) precluded counterbalancing and may introduce order effects.
• Session duration and sequence may induce fatigue, especially in controls.
• Potential unmeasured contextual factors (e.g., personality traits, motivation) could influence outcomes.
• No neurophenomenological or in-situ experiential sampling to directly link subjective phenomenology with neural dynamics. Future studies should incorporate experiential sampling and longitudinal designs to better characterize state/trait changes and mechanisms.