Perceived stress and cardiac autonomic function among Indian medical undergraduates: A cross-sectional heart rate variability study

BACKGROUND: Chronic stress is linked to impaired academic performance, emotional strain and autonomic dysregulation. Heart rate variability (HRV) is an objective, non-invasive marker of autonomic function. However, Indian undergraduate cohorts remain underrepresented in integrative studies combining perceived stress, HRV and lifestyle correlates within the competency-based curriculum framework. OBJECTIVES: To assess the prevalence and dominant domains of perceived stress using the Medical Students' Stressor Questionnaire (MSSQ), and analyse associations between perceived stress and HRV parameters among MBBS students. METHODS: In this cross-sectional study, 406 MBBS students across four academic years at a government medical college were assessed using the MSSQ-40. Resting 10-s ECG recordings were used to derive ultra-short-term time-domain HRV indices. Group comparisons were performed using non-parametric methods, and multivariable ordinal logistic regression was used to identify factors independently associated with perceived-stress severity. RESULTS: Overall, 77.09% of students reported moderate-to-high perceived stress. Academic-related and teaching-learning-related stressors were prominent contributors to the overall stress profile. HRV indices did not differ significantly across mild, moderate and high stress categories in the overall cohort. Academic-year groups showed differences in selected HRV indices, including RMSSD; however, these differences did not follow a consistent monotonic pattern across academic seniority. In multivariable ordinal logistic regression, sex, balanced-meal frequency, leisure engagement, physical activity and academic year were not independently associated with stress severity after correction for multiple comparisons. CONCLUSION: Perceived stress was common among Indian medical undergraduates, particularly in academic and teaching-learning domains. Broad perceived-stress categories were not associated with significant differences in ultra-short-term ECG-derived HRV. Selected HRV indices varied across academic-year cohorts, but these cross-sectional findings should be considered exploratory and should not be interpreted as evidence of progressive autonomic change during medical training.