Influence of resilience on autonomic nervous system habituation to repeated stress exposure: Insights from heart rate variability and heart rate response

Background and objectives: This study examines resilience's role in modulating autonomic nervous system (ANS) responses to repeated psychosocial stress, assessed via heart rate variability (HRV) and heart rate (HR) changes. Design and methods: Sixty healthy males completed the Trier Social Stress Test (TSST) across four sessions, each with six stress phases, to evaluate acute stress response and physiological habituation. Resilience, measured by the Brief Resilience Scale (BRS), was analyzed in relation to HR, HRV indices. Results: Resilient individuals exhibited better physiological recovery after acute stressor, with increased RMSSD and SDNN post-stress and reduced HR, peak HR, and delta HR for repeated stressor. While HR parameters habituated to repeated stress, anticipatory anxiety (pre-TSST STAI) increased, highlighting a distinction between physiological adaptation and psychological stress anticipation. Despite RMSSD, SDNN and LF recovery after acute stressor, resilience did not significantly impact high-frequency (HF) power. Conclusion: Resilience appears to enhance physiological recovery after acute stressor and adaptive physiological regulation under repeated stress, supporting its role as a protective factor. These findings have implications for interventions aimed at strengthening stress resilience and reducing allostatic load.