Sharing exerts from original articles on HRV, published on Harvard University Health Blog (2017) and Oura website 2020.
What is HRV?
As popular as the metaphor may be, a healthy heart doesn’t beat as regularly as a metronome—it actually changes its rhythm with each beat. This constant variation in milliseconds between your heartbeats is known as your heart rate variability (HRV).
HRV is simply a measure of the variation in time between each heartbeat. This variation is controlled by a primitive part of the nervous system called the autonomic . . .