Effects of Mindfulness-Based Intervention on Linear and Nonlinear Heart Rate Variability Measures: A Randomized-Control Trial

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 findings on this mechanism remain mixed. In this randomized controlled trial, 25 first-year college students were assigned to either a six-week mindfulness training 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, DFA α1) indices of heart rate variability (HRV) were compared across groups. Although both groups reported significant post-intervention reductions in stress and anxiety, participants in the mindfulness condition exhibited significantly higher cardiac entropy and lower DFA α1 values in response to acute stressors, with no corresponding differences in heart rate or RMSSD. These findings suggest that MBIs may modulate autonomic stress reactivity by enhancing the complexity and flexibility of cardiac dynamics, thereby supporting more adaptive physiological responses to stress. This pilot study extends prior work by demonstrating that nonlinear HRV metrics may be particularly sensitive to mindfulness-related changes in cardiovascular regulation under acute stress.