Heart rate variability (HRV) is the measure of the variation in time intervals between consecutive heartbeats. It reflects the autonomic nervous system's (ANS) regulation of the heart and is an important indicator of cardiovascular health, stress levels, and overall physiological resilience. The heart does not beat at a consistent rate; rather, the time intervals between beats can vary. These variations are influenced by several factors, including breathing, physical activity, emotional states, and even time of day.
