Heart Rate Variability

The variation in time intervals between consecutive heartbeats, reflecting the balance between sympathetic (stress response) and parasympathetic (rest and recovery) branches of the autonomic nervous system. HRV is used as an objective measure of stress, emotional state, and physiological resilience. Lower HRV often indicates stress or cognitive load, while higher HRV suggests relaxation and adaptability. In accessibility research, HRV provides a non-invasive, objective measure of stress that does not rely on self-report, making it valuable for populations who may have difficulty with interoception or emotional self-assessment.