Fig. 2: Effect on alpha wave dynamics.

a Bar plots show the peak amplitude, band-width, and frequency for the alpha band computed using the FOOOF toolbox for the P4 channel. The middle panel highlights the selected channel on the topomap. Pairwise comparisons are shown using brackets with significance p < 0.0001. We saw significant reductions in peak alpha amplitude between breathing (pranayama, kriya) and yoga nidra phases coupled with the decrease of band width during yoga nidra period. b Topomap plots for the peak amplitude, band-width and peak frequency for the alpha 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. The most significant changes in activity were observed in the parietal and occipital areas for the peak alpha amplitude and the fronto-parietal areas for the alpha band width. c Change of peak alpha amplitude (dB) of the P4 channel across time during pranayama, kriya, and yoga-nidra phases. The colored line denotes the peak alpha 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 each phase were not plotted. We see a slow decrease in the alpha amplitude during the kriya phase which sharply drops during the yoga-nidra phase highlighting the transition to a relaxed state with reduced feedback signals denoted by the reduction in alpha amplitude.