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

The study addresses a gap in neuroscientific research on Yogic mind–body practices, particularly Isha Yoga. Prior EEG work on meditation often reports increased theta, alpha, and gamma power linked to relaxed alertness, but pranayama and deconstructive/non-dual practices remain understudied. The authors aim to examine how different Isha Yoga practices (sukha kriya pranayama, breath-watching, shoonya) influence neurophysiology and psychological outcomes across groups differing in meditation proficiency (controls, novices, advanced). They hypothesize: (1) differential oscillatory dynamics across practices with greater power during attentional practices (pranayama, breath-watching); (2) trait differences at rest in advanced meditators (elevated frontal midline theta) and state relaxed alertness (increased low- and high-frequency power) during pranayama and breath-watching in meditators but not controls; (3) better psychometrics (lower stress/distress, higher well-being, non-attachment) and deeper meditation states in advanced meditators.

Background literature indicates meditation benefits attention, emotion regulation, and well-being and is associated with EEG markers of relaxed alertness (increased theta/alpha/gamma). Attentional (e.g., breath-focused), constructive (e.g., reappraisal), and deconstructive/non-dual practices may have distinct mechanisms and neural signatures. Pranayama is a preparatory yogic breath practice linked to rapid stress reduction and physiological benefits, yet EEG studies on pranayama are limited. Isha Yoga encompasses multicomponent practices (e.g., Shambhavi Mahamudra Kriya, Shoonya, Samyama) with prior findings of cardiovascular, neurophysiological, immune, and mental health benefits. Non-dual states (e.g., Shoonya) are characterized phenomenologically by reduced self–other boundaries, but neural evidence remains sparse. The study integrates these practices within a single EEG and psychometrics framework, using the phenomenological matrix model to situate findings.

Design: Cross-sectional study comparing advanced Isha meditators (ADV), novice Isha meditators (NOV), and meditation-naïve controls (CNT). Participants: N=103 (ADV n=42; NOV n=33; CNT n=28). Advanced meditators had completed at least one Samyama retreat; novices had not. Controls had no yoga/meditation exposure. Groups matched on age, education, and socioeconomic background. Mean (SD) age: ADV 35.57 (6.81), NOV 31.66 (7.64), CNT 31.14 (6.38). Lifetime Isha practice hours: ADV 5507.80 (2897.44), NOV 1637.24 (1126.61). Inclusion/exclusion in Supplementary File. Ethics approval obtained; informed consent provided. Procedure: EEG recorded continuously across sessions: Rest1 (eyes open/closed alternating), pranayama (sukha kriya; 6 min), breath-watching (15 min), cognitive task (visual oddball; not reported here), shoonya meditation (15 min). Each practice preceded and followed by 4-min rest with alternating eyes-open/closed. A washout after Rest2 preceded the cognitive task. Meditation depth questionnaires administered after Rest2 (post breath-watching) and Rest4 (post shoonya). Controls received instructions analogous to the practices (alternate nostril breathing, breath-watching, sit-still meditation with shoonya-like instructions). Practice order was fixed to adhere to traditional sequencing. EEG acquisition and preprocessing: 128-channel Geodesic EEG System 300, 1 kHz sampling, 24-bit, in a sound-attenuated chamber (25°C; 40–60% humidity). Online reference near Cz, ground near AFz. Data imported to EEGLAB (MATLAB R2021b), resampled to 250 Hz, average re-referenced, high-pass 0.5 Hz, low-pass 80 Hz, notch 50 Hz. Artifact Subspace Reconstruction (ASR; 5 SD threshold) used for bad channels/segments (mean % data removed: ADV 11.19, NOV 12.61, CNT 11.21). ICA (infomax) with ICALABEL (90% threshold) removed ocular, muscle, ECG artifacts (mean ICs removed: ADV 3.14, NOV 2.41, CNT 3.99). Spherical spline interpolation applied. Measures: Perceived Stress Scale (PSS-10); PHQ-4 (anxiety/depression); WHO-5 Well-Being Index; Non-Attachment Scale (NAS-7); Meditation Depth Questionnaire (MEDEQ; total and 5 clusters: hindrances, relaxation, concentration, essential qualities, non-duality); Stanford Sleepiness Scale (SSS; categorized as Alert vs Not Alert). Internal consistencies reported as good to excellent. EEG analyses: Band power (delta 1–4 Hz, theta 4–8, alpha 8–12, beta 13–30, gamma 30–80) extracted from 2-s epochs using Hamming window, 0.5-Hz resolution. Statistical comparisons via LIMO toolbox with robust t-statistics, 2000 permutations, threshold-free cluster enhancement (TFCE), and family-wise error correction (alpha < 0.05). Psychometric analyses: Conducted in R with appropriate parametric/non-parametric tests (Welch ANOVA or Kruskal–Wallis; Games–Howell or Dunn post-hoc; Holm correction). Effect sizes with 95% CI. Pearson correlations for associations; p < 0.05.

Resting state (trait effects; RC1): Advanced meditators vs controls showed higher frontal midline theta and lower centro-occipital gamma. Advanced vs novice: advanced had globally higher theta and alpha, and higher beta in fronto-midline/central regions. Novice vs controls: novices had lower alpha (left posterior) and lower localized centro-occipital gamma. Baseline differences were more pronounced between advanced and novice than between advanced and controls. Pranayama (PY vs RC1; within groups): Controls showed increased anterior delta and frontal midline theta, with no major changes in other bands. Both novice and advanced meditators showed increased power across all bands; novices exhibited global increases, advanced showed more localized increases. Pranayama (between groups): Novice vs controls: novices had greater power in posterior theta, frontal/central beta, and frontal/central/occipital gamma. Advanced vs controls: greater gamma in select frontal/occipital sites; little difference between advanced and novices (trend toward higher power in novices). Overall, pranayama increased power across bands in meditators, while controls increased only low-frequency bands; novices (lowest baseline power) showed the largest state changes. Breath-watching (BW vs RC1; within groups): Controls increased anterior delta/theta, decreased occipital alpha, and showed no major beta/gamma changes. Novice and advanced meditators showed significant global increases in delta, theta, and beta, with minimal alpha/gamma changes. Between groups: no significant differences among groups, though trends suggested higher alpha/beta/gamma in meditators. Shoonya (SS vs RC3; within groups): Controls showed global power decreases across all bands. Novices showed global reductions, especially in delta, beta, and gamma. Advanced meditators showed no significant power change from rest to shoonya (sustained power). Shoonya (between groups): Advanced > controls: globally greater power across all bands. Advanced > novices: globally greater power in all bands except delta. Novices > controls: greater power in all bands but confined to limited regions. Post–pre shoonya rest: no differences in advanced; localized reductions across bands in novices; widespread reductions across bands in controls. Psychometrics (group differences): Significant differences among groups for perceived stress (Kruskal–Wallis χ² = 12.39, p < 0.001, η²ordinal = 0.12), WHO well-being (χ² = 20.33, p < 0.001, η²ordinal = 0.20), non-attachment (χ² = 18.42, p < 0.001, η²ordinal = 0.18), and mental distress PHQ-4 (χ² = 18.09, p < 0.001, η²ordinal = 0.18). Post-hoc: advanced < controls for perceived stress, and advanced > controls for WHO well-being, non-attachment, with lower mental distress (all pHolm < 0.001). Advanced > novices for WHO well-being (pHolm < 0.05). Novices > controls for WHO well-being (pHolm < 0.05), non-attachment (pHolm < 0.001), and lower mental distress (pHolm < 0.05). Correlations with lifetime practice hours (n=103): Perceived stress r = −0.36, t(101) = −3.84, p < 0.001; mental distress 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 (MEDEQ): Breath-watching depth differed among groups (Welch F(2,44.17) = 20.59, p < 0.001, ω² = 0.45); post-hoc 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 differed (Welch F(2,39.75) = 26.98, p < 0.001, ω² = 0.55); post-hoc 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; novices showed improvements over controls in several clusters. Alertness (SSS): Before breath-watching, Alert: ADV 95%, NOV 84%, CNT 80%; after breath-watching, Alert: ADV 78%, NOV 72%, CNT 52%. Before shoonya, Alert: ADV 81%, NOV 90%, CNT 92%; after shoonya, Alert: ADV 97%, NOV 93%, CNT 62%.

Findings support that Isha Yoga practices induce a state of relaxed alertness—co-occurring increases in low-frequency (relaxation/stability) and high-frequency (alertness/clarity) oscillations—particularly in meditators during pranayama and breath-watching. Advanced meditators exhibit trait markers at rest (elevated frontal midline theta, alpha, beta), consistent with long-term practice-related neuroplasticity and heightened tonic alertness. During pranayama, both controls and meditators showed increases in frontal midline theta (linked to ACC/CAN activity and relaxation), but only meditators showed robust high-frequency increases, suggesting practice-dependent capacity to maintain wakeful clarity. Breath-watching elicited relaxed alertness in meditators, whereas controls showed signs of drowsiness (increased theta, decreased alpha) and reported more hindrances, indicating attentional difficulty without prior training. Shoonya (a deconstructive, non-dual practice) revealed distinct dynamics: novices and controls decreased power across bands (possibly reflecting reduced network synchronization and increased hindrances/drowsiness), while advanced meditators sustained power and reported higher non-duality, consistent with stable non-dual awareness states and trait-like stillness across rest and practice. Psychometrics corroborated neural findings: greater well-being and non-attachment, and lower stress/distress with more practice hours, and deeper meditation depth in advanced practitioners. Integrating results within the phenomenological matrix model, advanced meditators demonstrate higher dereification, meta-awareness, clarity, stability, and lower effort during breath-watching and shoonya than novices and controls.

Isha Yoga practices produce distinct neurophysiological and psychological signatures. Meditators, especially advanced practitioners, show trait resting-state alterations and state-dependent relaxed alertness during pranayama and breath-watching. During shoonya, advanced meditators maintain stable oscillatory dynamics and report non-dual experiences, whereas novices and controls show global power reductions. Greater lifetime practice associates with lower stress/distress, higher well-being and non-attachment, and deeper meditation. These findings elucidate brain signatures of Isha Yoga and support mind–body practices as potential avenues for enhancing mental health. Future research should employ longitudinal designs, control for session order/fatigue, include experiential sampling for neurophenomenology, and further dissect mechanisms of non-dual practices like shoonya.

Cross-sectional design precludes causal inference. Fixed practice order could introduce order effects; long session durations may induce fatigue (especially in controls). Potential unmeasured contextual factors (e.g., personality, motivation) may influence outcomes. No neurophenomenological/experience sampling approach was employed to capture moment-to-moment subjective states. Movement-based Isha components were excluded due to EEG artifact constraints, limiting generalizability across the full practice repertoire.