Meditation-Related Increases in EEG Fractal Dimension Reveal Enhanced Brain Complexity

Meditation has been proposed to alter large-scale brain dynamics, but its impact on neural complexity remains subtly yet incompletely understood. In this study, we investigated how three contemplative traditions, Himalayan Yoga Tradition, Vipassana, and Isha Shoonya Yoga, modulate electroencephalography (EEG) complexity, quantified via Higuchi’s Fractal Dimension (HFD). Based on the Entropic Brain Hypothesis, we hypothesized that regular meditative practice would be associated with increased EEG complexity relative to a non-meditative condition. We used a publicly available EEG dataset. In the original study, written informed consent was obtained, and the protocol was approved by the local MRI (India) ethics committee and the UC San Diego IRB (#090731). EEG data were recorded from 48 participants (16 per meditation group) and a non-meditating control group during two 20-minute blocks: meditation (including an initial breath-focused phase) and instructed mind-wandering. After standard preprocessing (filtering, artifact rejection, ICA) and segmentation into short overlapping epochs, HFD was computed for each electrode. The parameter Kmax was optimized by inspecting the HFD–Kmax curve across subjects, yielding a stable plateau around Kmax = 10, which was adopted for all subsequent analyses. Cluster-based paired permutation tests were used to compare breath focus, full meditation, and mind-wandering within each group. Across meditation traditions, we observed a robust increase in HFD during meditation relative to instructed mind-wandering, with the strongest effects during the breath-focus phase, indicating higher brain signal complexity in meditative states. These findings support the Entropic Brain Hypothesis by suggesting that meditation shifts neural activity toward regimes of enhanced complexity, and highlight EEG fractal metrics as sensitive markers of meditation-induced changes in brain dynamics.