Mindfulness-based intervention alters nonlinear heart rate variability in a pilot study

Mindfulness-based interventions (MBIs) have been consistently associated with reductions in perceived stress and anxiety. One proposed mechanism underlying these effects involves a shift toward parasympathetic dominance during stress exposure, facilitating enhanced emotion regulation and physiological adaptability; however, empirical evidence on this mechanism remains inclusive. In this randomized controlled trial, 25 first-year college students were assigned to either a six-week MBI program or an active control condition. Psychophysiological responses to acute stressors were assessed in conjunction with self-reported measures of stress and anxiety, both before and after the intervention. Linear (RMSSD) and nonlinear (sample entropy and DFA α1) indices of heart rate variability (HRV) were compared between groups. Although both groups reported significant post-intervention reductions in stress and anxiety, participants in the MBI group exhibited significantly lower DFA α1 values in response to acute stressors as compared to the control group. No such differences were found for heart rate or RMSSD. These preliminary findings suggest that mindfulness may modulate the dynamic organization of autonomic stress responding during active challenge, and that nonlinear HRV metrics may be particularly sensitive to mindfulness-related changes in cardiovascular regulation under acute stress.