Fig. 3.

Mean physiological emotion regulation for all eight heart rate variability (HRV) indices at baseline and end-of-treatment for Veterans who received either cognitive processing therapy (CPT) or Sudarshan kriya yoga (SKY) for PTSD (per protocol). Top row: a: average difference between the maximum and minimum HR (HR max–min [bpm]), b: low-to-high frequency ratio (LF/HF), c: square root of the mean squared differences between successive R-R intervals (RMSSD [ms]), d: standard deviation of the IBI of normal sinus beats (SDNN [ms]). Bottom row: e: normalised high frequency power (HF-HRV [FFT n.u.]), f: absolute high frequency power (HF-HRV [FFT ms²]), g: peak frequency of the low frequency band (LF peak [Hz]), h: absolute low frequency power (LF-HRV [FFT ms²]). For all HRV indices except LF/HF ratio, higher values reflect better emotion regulation. * denotes significant (p < .05) group by time interaction effect. ^ denotes small-to-moderate effect size group difference at end-of-treatment