Heart Rate Variability (HRV) as an Objective Indicator of the Stress Response: Physiological Mechanisms, Diagnostic Potential, and Clinical Applications

Heart rate variability (HRV) has gained recognition as a biomarker of autonomic nervous system activity and the body's adaptive capacity. This review discusses the physiological foundations of HRV and its relationship to the body's response to both acute and chronic stress. The main methods of HRV measurement are: time-domain, frequency-domain, and nonlinear. These are presented, along with their advantages, limitations, and key technical requirements. Particular attention is given to the application of HRV in the diagnosis, treatment, and prevention of stress-related disorders such as depression and anxiety, as well as the potential use of HRV biofeedback and mobile monitoring technologies. The review highlights current limitations in interpretative standards, the influence of confounding factors, and the need for individualized analysis. The potential for artificial intelligence tools to personalize stress assessment is also discussed. Despite growing clinical interest, HRV requires further standardization and research to enhance its utility as a tool for assessing psychophysiological states.