Fig. 3: Effect on theta wave dynamics.

a Bar plots show the peak amplitude, band-width, and frequency for the theta band computed using the FOOOF toolbox for the PZ channel. The bottom panel highlights the selected channel on the topomap. Pairwise comparisons are shown using brackets with significance p < 0.0001. We saw significant changes in peak amplitude which was maximum during the kriya phase and sustained afterwards. The theta bandwidth increased during the yoga nidra period accompanied by a shift to a lower peak theta frequency value. b Topomap plots for the peak amplitude, band-width, and peak frequency for the theta waves across the various parts of the SKY meditation -pre-resting state, pranayama breathing, kriya breathing, yoga-nidra, post-resting state. Dots on the channels signify statistical significance at p < 0.00001 from a repeated measures ANOVA ran across the five phases of SKY per channel individually. We saw the most significant changes in the peak amplitude in frontal, temporal and parietal channels. Band-width and peak frequency changes were significant along the temporal, parietal-central, and occipital channels. c Change of peak theta amplitude (dB) of the PZ channel across time during pranayama, kriya, and yoga-nidra phases. The colored line denotes the peak theta value at each time point, the light color bar is the standard deviation across subjects and the black line denotes the moving average of the mean signal with a window of 4 s. The yoga-nidra phase was divided into the silent (green) and guided instructions (blue) parts as highlighted in the third panel. The first 100 s in each phase were not plotted. We observe sharp increases in theta power during the kriya and yoga-nidra phases. The dip during the yoga-nidra period denotes the transition to audio-guided meditation instructions after the end of silence period. We found that the theta rhythms increased during the kriya phase and were sustained during the yoga nidra period as well.