Emotions are Reflected in Heart Rate Variability, the Patterns Between Heartbeats

interview with
Rollin McCraty

Artwork by

Benju Pan



Table of Contents

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The 4 primary ways heart communicates with brain and body

Our core work over the years has been psychophysiology. It has especially been about how the heart and brain communicate. Our focus has been on how the heart communicates back to the brain—or really to the brain—and how the activity of the heart/quality of the neural signals will affect brain function. It is quite surprising all the ways that the activity of the heart affects our brain and perceptions of the world. There are four primary ways that the heart communicates with the brain and body.

1. Neurological pathway

The one I’ll talk about most is neurological. In fact, what I’m about to tell you is not new, but it’s surprising to most people—even physicians and neuroscientists. The heart sends more neural signals to the brain than the brain sends to the heart.
That’s been known since the late 1800s. This is basic anatomy, and it’s just been forgotten and kind of rediscovered more recently.

2. Hormonal pathway

Hormonally is another way that the heart communicates with the brain and body. It was in the mid-’80s that the heart was reclassified to be part of the interveinal hormonal system, with the discovery of the HO peptide.
Its nickname is the balance hormone. It has a balancing effect on the cardiovascular system. A higher HO peptide blocks the effects of stress hormones at the level of the adrenal glands.

Then it was discovered that the heart secretes all the catecholamines, like dopamine, and noradrenaline… Then the most recent discovery was that the heart secrets oxytocin. In fact, the heart secretes as much oxytocin as the brain.
Its nickname or the media loves to call it the “love hormone,” if you will. 

3. The bio-physical pathway

‘Bio-physically’ is what I call pressure waves. Every time the heart beats, we have a pressure wave.

What we feel is our pulse. It’s the pressure wave that’s transmitted down through the arteries. It turns out the pressure wave which we can measure quite easily on your earlobe, or your fingers, or your toe, modulates. It has a way of synchronizing all the cells. Information is carried in the pressure wave.

flowers growing from the heart
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4. The magnetic pathway

The fourth way, at least that we know if, is energetic magnetically. Whenever we have a flow of current, we produce a magnetic field. The magnetic field penetrates quite easily through human tissues, so the magnetic field generated by the heart extends external to the body, and is measured with devices called magnetometers.

Of course, when we put electrodes across the heart to measure the electrocardiogram, we’re measuring electricity. We’re measuring a flow of current when we put electrodes across the heart, or the chest, or the brain.

But whenever we have a flow of current, we know that you produce a magnetic field. Electric and magnetic fields are very different animals. Although we call it electromagnetism, electric and magnetic are quite different.

Emotions live in the space between heartbeats, according to research

We spent a lot of our early years understanding heart rate variability. One of our earlier observations was that the best single measure of detecting a person’s emotional state is the rhythms of the heart. That’s what lead us down the path of understanding heart rate variability. 

flowers growing from the heart

Understanding the language of heart rate variability

In a healthy, resilient person, our heart rate is changing with every heartbeat, so that’s called the heart rate variability. The time between each pair of heartbeats is what you measure, and that time between heartbeats is always changing if we’re healthy. We have more of it when we’re young. It gets less as we age, in a pretty linear relationship. In fact, we can measure somebody’s HRV in one minute now and tell in about two years how old they are just from that measurement. So, it’s one of the best measures we know of, of aging. Our physiological and chronological aging is matched. Usually, if they’re not, that’s because we’ve either got some type of chronic or disease process or more commonly, a lot of stress going on in our lives, which puts more wear and tear on the system. Our HRV becomes lower than it should be.

That’s important clinically because low HRV, relative to our age, is a stronger predictor of future serious health problems than what your cholesterol level is, or your blood pressure, whether you smoke or not, and pretty much all of these standards are well-known risk factors. It’s really exploding in clinical medicine now. Measuring HRV for reassessing how depleted somebody is, is the way from an energy perspective. It also reflects in my field, more psychophysiology, a person’s resilience. It also directly relates to our psychology.

People with higher variability tend to be able to self-regulate themselves better. That is not to charge something on the credit card if you’re on a budget or eat that piece of cake if you’re on a diet. 

It is the ability to inhibit our impulses. To engage socially, it is to inhibit and work things out if we don’t agree. It is to be able to inhibit and get ourselves into a more coherent state and connect more energetically as well as socially with people.

Rhythms of emotion

Understanding this was an important discovery. Emotions are reflected in the heart rate variability, the patterns between heartbeats, the pattern of those changes. And a way to think of that, a good analogy, is morse code. Some of you might be old enough to remember morse code, where you can communicate information by the intervals, the time between things. 

Morse code is a very simple version. You’ve got two long or short intervals. The heart’s basically doing the same thing. In fact, not just the heart; it’s the way physiology encodes information in the brain the way one neuron talks to another neuron, all of the information is in the inter-spike intervals, the time between the spikes.

That’s all that matters. It’s where the information is. I’m just suggesting the heart’s doing the same thing, but at a global scale, so these timings between heartbeats is a way of encoding information that can be communicated to the whole body and externally. 

There’s a little bit more to that, but it gives you the idea, a way to think of it. The next step in our research was seeing how these patterns of neural information from the heart (the afferent or the ascending pathways) back up to the brain, modulate perception, cognitive function, and our capacity to maintain our composure self-regulate.

Then that unfolded into understanding how it had a lot to do with creating our actual emotional experience. The felt quality of emotion has a lot to do with these rhythms of the heart.

For example, there’s a direct, ascending neural pathway that comes up to the medulla, and then directly to the amygdala. In fact, the neural activity in the core nucleus of the amygdalas is synchronized to the heart. So, whatever the rhythm of the heart is, the amygdala is seen in real-time. That has a lot to do with creating an emotional experience and how it’s interpreting those patterns.

flowers growing from the heart

Scientists decode the heart’s magnetic field to detect discrete emotions

The magnetic field penetrates quite easily through human tissues, so the magnetic field generated by the heart extends external to the body and is measured with devices called magnetometers.

With today’s magnetometers, you lose the ability to detect the magnetic field produced by the heart about three feet outside of the body. Now, with the same instrument, just to give some relative measurements here, with the same settings, you lose the ability to detect a brainwave about an inch away. 

The heart is the big player in our physiology and psychophysiology, so every cell in our body feels that magnetic field, as do other people around us. In our research, it was shown that the magnetic field radiated by the heart acts kind of like a cellphone.

I’m an ex-Motorola guy in my previous life, so we know a lot about how to use magnetic fields to carry information. It’s how our cell phone gets the information from our phone to the cell tower, right? It’s the electromagnetic field that we modulate or put the information to carry it from one place to another, and it’s the magnetic component that allows our cellphones to work inside of buildings and things because it goes through the walls and so on and gets to the cell tower.

Well, as it turns out, we work the same way. Magnetic fields are carrying the same information just like a cellphone would be. Part two of that is, not only are we radiating these magnetic fields carrying information, but you can also decode that information. One of my colleagues has taken our work and shown that just by measuring the field, the information, and decoding it, you can have about 75 percent accuracy detecting discrete emotional states.

Certainly, our heart is communicating with us and our brain. I’m not saying it’s heart or brain. It’s really about integrating the two. As it turns out, having a coherent heart is one of the best ways to really maximize our brain. Yes, our hearts communicate with our brains, but it’s also communicating externally. The nervous systems of other people are like big antennas. So we certainly detect and decode that information in meaningful and physiologically relevant ways.

Thank you for reading this article to the end and giving us so much of your precious attention.

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Rollin McCraty

Writer | Contributor

Benju Pan


Benju Pan grew up in Neverland and never left Neverland. You might see him around in your dreams and imagination. And you’ll feel his presence when you listen to your heart.

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