The BERTHA Project is proud to present findings from the paper Exploring the Nexus Between Physical and Mental Health: Assessing Stress Through Heart Rate Variability, showcased at the Human Interaction and Emerging Technologies (IHIET-AI 2025): Artificial Intelligence and Future Applications conference, from June 10-12, 2025, in University of East London, United Kingdom..

This study explores how electrocardiography (ECG)-derived heart rate variability (HRV) parameters can objectively assess acute stress, offering a physiological bridge between physical and mental health.

Participants underwent a validated stress-inducing protocol using the Cold Pressor Test (CPT), with ECG data collected across three phases:

• Baseline (resting state)
• Stressor (hand immersion in cold water)
• Recovery (post-stress rest)

A wide range of HRV parameters were analyzed, including:

• Time-domain metrics (e.g., mean NN intervals, RMSSD, SDNN)
• Frequency-domain metrics (e.g., LF/HF ratio)
• Geometric and non-linear indices (e.g., SD1, SD2, CVI)

Key Highlights and Findings

• Acute stress reliably altered HRV parameters, with increased heart rate and reduced NN intervals indicating sympathetic nervous system activation.
• Unexpected increases in parasympathetic-related measures (e.g., RMSSD, SDNN) during stress suggest participants used controlled breathing to cope with discomfort.
• Age significantly influenced HRV responses, with older participants showing reduced autonomic adaptability and blunted stress responses.
• Frequency-domain measures were less consistent, likely due to short measurement windows and respiratory modulation.
• Non-linear and geometric indices revealed increased complexity during stress, challenging traditional assumptions of reduced variability under stress.

Implications for Mental Health and Personalized Care

These findings support HRV as a non-invasive, objective biomarker for stress, with potential applications in:

• Mental health diagnostics (e.g., anxiety, depression)
• Biofeedback and stress management tools
• Personalized interventions tailored to age and coping strategies

The study emphasizes the need for standardized HRV protocols and highlights the role of behavioral adaptations in shaping physiological stress responses.

Acknowledgment: Research conducted under the BERTHA project (GA101076360), funded by the European Union. Views expressed are those of the authors and do not necessarily reflect those of the EU or CINEA.