The Heart–Brain Connection
Most of us have been taught in school that the heart is constantly responding to “orders” sent by the brain in the form of neural signals. However, it is not as commonly known that the heart actually sends more signals to the brain than the brain sends to the heart! Moreover, these heart signals have a significant effect on brain function—influencing emotional processing as well as higher cognitive faculties such as attention, perception, memory, and problem-solving. In other words, not only does the heart respond to the brain, but the brain continuously responds to the heart.
The effect of heart activity on brain function has been researched extensively over about the past 40 years. Earlier research mainly examined the effects of heart activity occurring on a very short time scale—over several consecutive heartbeats at maximum. Scientists at the Institute of HeartMath have extended this body of scientific research by looking at how larger-scale patterns of heart activity affect the brain’s functioning.
HeartMath research has demonstrated that different patterns of heart activity (which accompany different emotional states) have distinct effects on cognitive and emotional function. During stress and negative emotions, when the heart rhythm pattern is erratic and disordered, the corresponding pattern of neural signals traveling from the heart to the brain inhibits higher cognitive functions. This limits our ability to think clearly, remember, learn, reason, and make effective decisions. (This helps explain why we may often act impulsively and unwisely when we’re under stress.) The heart’s input to the brain during stressful or negative emotions also has a profound effect on the brain’s emotional processes—actually serving to reinforce the emotional experience of stress.
In contrast, the more ordered and stable pattern of the heart’s input to the brain during positive emotional states has the opposite effect—it facilitates cognitive function and reinforces positive feelings and emotional stability. This means that learning to generate increased heart rhythm coherence, by sustaining positive emotions, not only benefits the entire body, but also profoundly affects how we perceive, think, feel, and perform.
Your Heart’s Changing Rhythm
The heart at rest was once thought to operate much like a metronome, faithfully beating out a regular, steady rhythm. Scientists and physicians now know, however, that this is far from the case. Rather than being monotonously regular, the rhythm of a healthy heart—even under resting conditions— is actually surprisingly irregular, with the time interval between consecutive heartbeats constantly changing. This naturally occurring beat-to-beat variation in heart rate is called heart rate variability (HRV).
Heart rate variability is a measure of the beat-to-beat changes in heart rate. The diagram on the next page shows three heartbeats recorded on an electrocardiogram (ECG). Note that variation in the time interval between consecutive heartbeats, giving a different heart rate (in beats per minute) for each interbeat interval.
The normal variability in heart rate is due to the synergistic action of the two branches of the autonomic nervous system (ANS)—the part of the nervous system that regulates most of the body’s internal functions. The sympathetic nerves act to accelerate heart rate, while the parasympathetic (vagus) nerves slow it down. The sympathetic and parasympathetic branches of the ANS are continually interacting to maintain cardiovascular activity in its optimal range and to permit appropriate reactions to changing external and internal conditions. The analysis of HRV therefore serves as a dynamic window into the function and balance of the autonomic nervous system.
The moment-to-moment variations in heart rate are generally overlooked when average heart rate is measured (for example, when your doctor takes your pulse over a certain period of time and calculates that your heart is beating at, say, 70 beats per minute). However, the emWave and Inner Balance technologies allows you to observe your heart’s changing rhythms in real time. Using your pulse data, it provides a picture of your HRV—plotting the natural increases and decreases in your heart rate occurring on a continual basis.
Why is HRV Important?
Scientists and physicians consider HRV to be an important indicator of health and fitness. As a marker of physiological resilience and behavioral flexibility, it reflects our ability to adapt effectively to stress and environmental demands. A simple analogy helps to illustrate this point: Just as the shifting stance of a tennis player about to receive a serve may facilitate swift adaptation, in healthy individuals the heart remains similarly responsive and resilient, primed and ready to react when needed.
HRV is also a marker of biological aging. Our heart rate variability is greatest when we are young, and as we age the range of variation in our resting heart rate becomes smaller. Although the age-related decline in HRV is a natural process, having abnormally low HRV for one’s age group is associated with increased risk of future health problems and premature mortality. Low HRV is also observed in individuals with a wide range of diseases and disorders. By reducing stress-induced wear and tear on the nervous system and facilitating the body’s natural regenerative processes, regular practice of HeartMath coherence-building techniques can help restore low HRV to healthy values.
Heart Rhythm Patterns and Emotions
Many factors affect the activity of the ANS, and therefore influence HRV. These include our breathing patterns, physical exercise, and even our thoughts. Research at the Institute of HeartMath has shown that one of the most powerful factors that affect our heart’s changing rhythm is our feelings and emotions. When our varying heart rate is plotted over time, the overall shape of the waveform produced is called the heart rhythm pattern. When you use the emWave and Inner Balance technologies, you are seeing your heart rhythm pattern in real time. HeartMath research has found that the emotions we experience directly affect our heart rhythm pattern—and this, in turn, tells us much about how our body is functioning.
In general, emotional stress—including emotions such as anger, frustration, and anxiety—gives rise to heart rhythm patterns that appear irregular and erratic: The HRV waveform looks like a series of uneven, jagged peaks (an example is shown in the figure below). Scientists call this an incoherent heart rhythm pattern. Physiologically, this pattern indicates that the signals produced by the two branches of the ANS are out of sync with each other. This can be likened to driving a car with one foot on the gas pedal (the sympathetic nervous system) and the other on the brake (the parasympathetic nervous system) at the same time—this creates a jerky ride, burns more gas, and isn’t great for your car, either! Likewise, the incoherent patterns of physiological activity associated with stressful emotions can cause our body to operate inefficiently, deplete our energy, and produce extra wear and tear on our whole system. This is especially true if stress and negative emotions are prolonged or experienced often.
In contrast, positive emotions send a very different signal throughout our body. When we experience uplifting emotions such as appreciation, joy, care, and love; our heart rhythm pattern becomes highly ordered, looking like a smooth, harmonious wave (an example is shown in the figure below). This is called a coherent heart rhythm pattern. When we are generating a coherent heart rhythm, the activity in the two branches of the ANS is synchronized and the body’s systems operate with increased efficiency and harmony. It’s no wonder that positive emotions feel so good—they actually help our body’s systems synchronize and work better.
The graphs on the next page show examples of real-time heart rate variability patterns (heart rhythms) recorded from individuals experiencing different emotions. The incoherent heart rhythm pattern shown in the top graph, characterized by its irregular, jagged waveform, is typical of stress and negative emotions such as anger, frustration, and anxiety. The bottom graph shows an example of the coherent heart rhythm pattern that is typically observed when an individual is experiencing a sustained positive emotion, such as appreciation, compassion, or love. The coherent pattern is characterized by its regular, sine-wave-like waveform. It is interesting to note that the overall amount of heart rate variability is actually the same in the two recordings shown below; however, the patterns of the HRV waveforms are clearly different.
“Living organisms, including people, exchange electromagnetic energy through contact between their fields, and this electromagnetic energy carries information in much the same way radio transmitters and receivers carry music. When people or other living organisms touch, a subtle but highly complex exchange of information occurs via their electromagnetic fields. The two fields begin to entrain or resonate with each other. The result is a combined wave that has an increased amplitude—both its power and depth are increased.” —Paul Lenda, Founder & Director of Shift>
Coherence: A State of Optimal Function
The Institute of HeartMath’s research has shown that generating sustained positive emotions facilitates a body-wide shift to a specific, scientifically measurable state. This state is termed psychophysiological coherence, because it is characterized by increased order and harmony in both our psychological (mental and emotional) and physiological (bodily) processes. Psychophysiological coherence is a state of optimal function. Research shows that when we activate this state, our physiological systems function more efficiently, we experience greater emotional stability, and we also have increased mental clarity and improved cognitive function. Simply stated, our body and brain work better, we feel better, and we perform better.
Physiologically, the coherence state is marked by the development of a smooth, sine-wave-like pattern in the heart rate variability trace. This characteristic pattern, called heart rhythm coherence, is the primary indicator of the psychophysiological coherence state, and is what the emWave and Inner Balance technologies measure and quantify. A number of important physiological changes occur during coherence. The two branches of the ANS synchronize with one another, and there is an overall shift in autonomic balance toward increased parasympathetic activity. There is also increased physiological entrainment—a number of different bodily systems synchronize to the rhythm generated by the heart. Finally, there is increased synchronization between the activity of the heart and brain.
The Intelligent Heart
Many of the changes in bodily function that occur during the coherence state revolve around changes in the heart’s pattern of activity. While the heart is certainly a remarkable pump, interestingly, it is only relatively recently in the course of human history—around the past three centuries or so— that the heart’s function has been defined (by Western scientific thought) as only that of pumping blood. Historically, in almost every culture of the world, the heart was ascribed a far more multifaceted role in the human system, being regarded as a source of wisdom, spiritual insight, thought, and emotion. Intriguingly, scientific research over the past several decades has begun to provide evidence that many of these long-surviving associations may well be more than simply metaphorical. These developments have led science to once again revise and expand its understanding of the heart and the role of this amazing organ.
In the new field of neurocardiology, for example, scientists have discovered that the heart possesses its own intrinsic nervous system—a network of nerves so functionally sophisticated as to earn the description of a “heart brain.” Containing over 40,000 neurons, this “little brain” gives the heart the ability to independently sense, process information, make decisions, and even to demonstrate a type of learning and memory. In essence, it appears that the heart is truly an intelligent system. Research has also revealed that the heart is a hormonal gland, manufacturing and secreting numerous hormones and neurotransmitters that profoundly affect brain and body function. Among the hormones the heart produces is oxytocin—well known as the “love” or “bonding hormone.” Science has only begun to understand the effects of the electromagnetic fields produced by the heart, but there is evidence that the information contained in the heart’s powerful field may play a vital synchronizing role in the human body—and that it may affect others around us as well.