Rollin McCraty: We started out our lab as basically a psychophysiology lab, and because of the intuitive experiences and insight, we were looking more at the heart. And more at positive emotions. This is back in the early 90s. And at that time, this is years, decades before the positive psychology movement.

Right? There were very few, maybe 3 or 4 papers in the official research published literature on things like compassion, or appreciation, or love. It was just non-existent. Thousands on depression and anxiety disorder and all that.

So very few people had actually looked at what happens physiologically when people actually sincerely feel love, or compassion, or kindness. So that's… so we started out, and we're looking it up. Usually, we chose appreciation as one of our first, because we'd already found that that's one of the easier... I tend to call them regenerative emotions rather than positive now.

That people can actually self-create and feel, okay? So anyway, we were looking at brain waves and all kinds of stuff, blood pressure and hormones and all this stuff back then. And what we found was that when people were feeling, whether it was appreciation or compassion or kindness, from the body perspective, what was most reflective of that state was actually reflected in the heart. But it's in the rhythm of the heart.

Okay, so this is where you talked about heart rate variability. So back then, nobody had ever heard of HRV, or heart rate variability. Which is the beat-to-beat change in heart rate. So, everyone knows what heart rate is, right?

How many times does the heart beat in a minute? But in reality, the heart rate is changing with every heartbeat. For HRV, you measure the time interval between each consecutive pair of heartbeats, and that's always changing. And what you see is that that's what gives us the heart rhythm.

Without that beat-to-beat variability, we would have no heart rhythm. And it's quite dramatic, actually, these B2B changes. And so what we found back then was that when people were feeling things like frustration, or impatience, or especially anxiety, or anger is way worse, is that the rhythm becomes very jerky and chaotic-looking. But something almost magical happened when people really felt appreciation, or love, or compassion, is that rhythm, not only did the pattern change, it shifted into a completely different mode of function.

Right? Which is what we call heart coherence now. And that took many years to understand why we're built that way, but all of the things that are going on internally that have to happen for that rhythm to shift into that state. And ultimately, it reflects that the activity in our brain and our nervous system is shifting into a different mode.

It's becoming more synchronized. And then chasing that rabbit down the hole, that underlies our ability to perform well, to think clearly, to maintain that inner stability. That we were talking about. All of those types of things.

I could… we could spend a whole session talking about what all has to go on to be in that nice, coherent sine wave. So the heart rhythm looks more like rolling hills or a sine wave pattern when you're in that coherent state.