Association of Neuroticism and Conscientiousness with Sympathovagal and Heart Rate Variability Indices in Medical Undergraduates
TL;DR
These findings support a cautious interpretation in which personality traits relate to resting autonomic patterning in medical students, while not implying causality or direct mechanistic inference.
Abstract
Objective: Heart rate variability (HRV) is widely used to characterise cardiac autonomic regulation, but the extent to which specific personality traits relate to short-term HRV indices in medical students remains uncertain. This study examined whether neuroticism and conscientiousness were associated with frequency-domain and time-domain HRV measures in first-year medical undergraduates. Methods: In this cross-sectional study, 100 first-year MBBS students aged 18-24 y underwent 5-minute resting ECG recording in the supine position after standard pre-recording stabilisation. HRV analysis was performed in Kubios HRV Scientific to derive SDNN, RMSSD, pNN50, low-frequency (LF) power, high-frequency (HF) power, and the LF/HF ratio. Personality was assessed with the Big Five Inventory, with primary analyses focused on neuroticism and conscientiousness. Pearson correlations and multivariable linear regression were used. Results: Neuroticism correlated positively with LF power (r=0.42, p<0.001) and LF/HF ratio (r=0.46, p<0.001), and negatively with pNN50 (r=-0.40, p<0.001) and HF power (r=-0.39, p<0.001). Conscientiousness showed the reverse pattern, with positive correlations for pNN50 (r=0.27, p=0.007) and HF power (r=0.27, p=0.007), and negative correlations for LF power (r=-0.29, p=0.004) and LF/HF ratio (r=-0.33, p=0.001). Neither trait was significantly associated with SDNN or RMSSD. In multivariable models, neuroticism remained an independent predictor of LF/HF ratio (B=0.037, p=0.007), pNN50 (B=-0.397, p=0.017), HF power (B=-11.965, p=0.017), and LF power (B=8.317, p=0.009), whereas the models for SDNN and RMSSD were not significant. Conclusion: In this cohort, neuroticism and conscientiousness were associated mainly with vagally weighted and spectral HRV indices rather than with global short-term variability. These findings support a cautious interpretation in which personality traits relate to resting autonomic patterning in medical students, while not implying causality or direct mechanistic inference.