Heart Rate Variability as a Marker of Autonomic Function in Medical Students During Stress: A Prospective Observational Study

Background: Medical students face significant academic and psychological stressors that may impact their autonomic nervous system (ANS) function. Heart rate variability (HRV), a non-invasive marker of autonomic function, has emerged as a valuable tool for assessing stress-related physiological changes. However, comprehensive studies examining HRV patterns in medical students during various stress conditions remain limited. The objective is to investigate HRV as a marker of autonomic function in medical students during academic stress and to examine the relationships between HRV parameters, perceived stress levels, and psychological well-being. Material and Methods: A prospective observational study was conducted with 120 medical students. HRV measurements were obtained using standardized 5-minute ECG recordings during baseline (low-stress) and examination (high-stress) periods. Time-domain parameters (SDNN, RMSSD, pNN50) and frequency-domain parameters (LF, HF, LF/HF ratio) were analyzed. Psychological assessments included the Perceived Stress Scale (PSS-10), Depression Anxiety Stress Scale (DASS-21), and Pittsburgh Sleep Quality Index (PSQI). Results: Significant reductions were observed in all HRV parameters during the high-stress period compared to baseline (SDNN: 52.6 ± 14.2 vs. 38.4 ± 12.6 ms; RMSSD: 46.8 ± 16.4 vs. 31.2 ± 11.8 ms; p < 0.001 for all). The LF/HF ratio increased significantly (0.82 ± 0.32 vs. 1.34 ± 0.48; p < 0.001), indicating sympathetic predominance. Strong negative correlations were found between HRV indices and PSS-10, DASS-21, and PSQI scores. Conclusion: HRV serves as a sensitive physiological marker for autonomic dysfunction in medical students experiencing academic stress. Poor sleep quality and high perceived stress are independent predictors of HRV impairment. These findings support the implementation of stress-management and sleep-hygiene interventions in medical education programmes.

Keywords: Heart rate variability, autonomic nervous system, medical students, academic stress, parasympathetic activity, sympathetic activity, stress biomarkers.