During meditation, brain activity patterns become more uniform across regions, as shown by EEG recordings from fifteen practitioners of Rajayoga meditation. The covariance matrices of neural activity between successive time windows become more similar, particularly in the frontal region, indicating reduced variability in brain connectivity during the meditative state compared to non-meditative states.
Chanting the OM mantra for 30 minutes produces significant changes in the delta brainwave band, which is associated with deep sleep, suggesting that OM meditation induces a deep-sleep-like state. Twenty-three novice meditators had their EEG signals recorded before and after chanting. Using stationary wavelet transform to extract five frequency bands and an SVM classifier with a radial basis kernel, the delta band showed the most notable shifts. This indicates that even brief OM mantra practice can alter brain activity toward a restful state.