Introduction to HRV: Understanding the Basics Heart Rate Variability (HRV) is an often-overlooked but crucial indicator of our overall well-being and stress levels. To understand HRV, it’s essential to start with the basics of what it represents and why it matters. HRV measures the variation in time intervals between heartbeats, known as inter-beat intervals. Unlike a regular heartbeat rate that might be consistently measured as 60 beats per minute, HRV focuses on the tiny differences in time between successive beats.