The Hidden Toll of On-Call Shifts: Reduced Heart Rate Variability and Increased Physiological Stress in Residents

OBJECTIVE: The aim of this study was to assess autonomic dysfunction via heart rate variability (HRV) in residents with on-call shifts. METHOD: A cross-sectional study of 140 residents (104 on-call, 36 non-on-call) was conducted. HRV parameters, stress indices, and physical activity (International Physical Activity Questionnaire, IPAQ) were compared using parametric and non-parametric tests. RESULTS: On-call residents showed elevated heart rates (84 vs. 79 bpm, P = 0.006), higher stress indices (12.1 vs. 9.96, P = 0.003), and reduced parasympathetic markers (root mean square of successive differences [RMSSD], standard deviation of normal-to-normal intervals [SDNN], parasympathetic nervous system index [PNS index]; all P ≤ 0.006). Physical activity did not differ between groups. CONCLUSION: An association between on-call shifts and altered autonomic balance was observed, suggesting a potential increase in cardiovascular risk independent of lifestyle factors. These findings may be considered by policymakers when planning resident physician workloads.