HRV is a method of assessing changes in the cardiac cycle1. Simply put, HRV “refers to the time between heartbeats,” explains Bradley Server, MD, FACC, board-certified interventional cardiologist and chief medical officer of CardioSolution. “Although most people have a relatively regular heart rate, there is always some variability in the time between individual beats.”

As for how your heart rate variability, autonomic nervous system, or ANS, works, monitors your heart rate2 and ultimately your HRV. The ANS includes sympathetic (“fight or flight”) and parasympathetic (“rest and digest”) responses.

“When the autonomic nervous system is in balance, there is a tendency for greater variability in the time between heartbeats,” Server said. “When the autonomic nervous system is out of balance due to increased stress (physiological or psychological), disease, or autonomic dysfunction, heart rate variability decreases.”

Your HRV depends on your age and gender, so there’s no exact number (it also fluctuates over time). Talk to your doctor to get a better idea of ​​the exact range you should be aiming for based on your health.