The concept of coherence is useful in understanding how physiological patterns change with the experience of different emotions. The term ’coherence’ has several related definitions, all of which are applicable to the study of human function. A common dictionary definition of the term is ’the quality of being logically integrated, consistent and intelligible,’ as in a coherent argument. In this context, thoughts and emotional states can be considered "coherent" or "incoherent." We describe positive emotions such as love or appreciation as coherent states, whereas negative feelings such as anger, anxiety or frustration are examples of incoherent states. Importantly, however, these
associations are not merely metaphorical. The research studies presented in this section provide intriguing evidence that different emotions lead to measurably different degrees of coherence in the oscillatory rhythms generated by the body’s systems.
Definitions of Coherence
Clarity of thought and emotional balance
The quality of being orderly, consistent, and intelligible (e.g.a coherent argument)
Synchronization between multiple systems
A constructive waveform produced by two or more waves that are phase or frequency-locked (e.g., lasers)
Ordered patterning within one system
An ordered or constructive distribution of power content within a single waveform; autocoherence (e.g., sine wave)
This leads us to a second use of the term "coherence." In physics, the term is used to describe two or more waves that are phase or frequency-locked together to produce a constructive waveform. A common example is the laser, in which multiple light waves phase-lock to produce a powerful, coherent energy wave. In physiology, the term is similarly used to describe a state in which two or more of the body’s oscillatory systems, such as respiration and heart rhythm patterns, become synchronous and operate at the same frequency. This type of coherence is called entrainment.
The term coherence is also used in mathematics to describe the ordered or constructive distribution of the power content within a single waveform. In this case, the more stable the frequency and shape of the waveform, the higher the coherence. A good example of a coherent wave is the sine wave. In the engineering and signal processing sciences, the term autocoherence is used to denote this type of coherence. When we speak of physiological coherence in this sense, we are referring to the degree of order and stability in the waveform that reflects the rhythmic activity of any given physiological system over a specified period of time. Interestingly, as shown below, we have found that in states in which there is a high degree of coherence within the HRV waveform, there also tends to be increased coherence between the rhythmic patterns produced by different physiological
oscillatory systems (e.g. synchronization and entrainment between heart rhythms, respiratory rhythms and blood pressure oscillations).
Physiological Coherence
A state characterized by:
High heart rhythm coherence (sine wave-like rhythmic pattern)
Increased parasympathetic activity
Increased entrainment and synchronization between physiological systems
Efficient and harmonious functioning of the cardiovascular, nervous, hormonal and immune systems
Our research has elucidated a clear and definable mode of physiological function that we call physiological coherence. This mode is associated with a sine wave-like pattern in the heart rhythms, a shift in autonomic balance towards increased parasympathetic activity, increased heart-brain synchronization and entrainment between diverse physiological systems. In this mode, the body’s systems function with a high degree of efficiency and harmony, and natural regenerative processes are facilitated. Although physiological coherence is a natural human state which can occur spontaneously, sustained episodes are generally rare. While specific rhythmic breathing methods may induce coherence and entrainment for brief periods, our research indicates that individuals can maintain extended periods of physiological coherence through actively self-generating positive emotions.
Using a positive emotion to drive the coherent mode allows it to emerge naturally, and results in changes in the patterns of afferent information flowing from the heart to the respiratory and other brain centers. This, in turn, makes it easier to sustain the positive emotional state and coherent mode for longer periods, even during challenging situations.
When the physiological coherence mode is driven by a positive emotional state, we call it psychophysiological coherence. This state is associated with sustained positive emotion and a high degree of mental and emotional stability. In states of psychophysiological coherence, there is increased synchronization and harmony between the cognitive, emotional and physiological systems, resulting in efficient and harmonious functioning of the whole. As we will see in subsequent sections, studies conducted across diverse populations have linked the capacity to self-generate and sustain psychophysiologically coherent states at will with numerous benefits. Observed outcomes include: reduced stress, anxiety and depression; decreased burnout and fatigue; enhanced immunity and hormonal balance; improved cognitive performance and enhanced learning; increased organizational effectiveness; and health improvements in a number of clinical populations.
Psychophysiological Coherence
A state associated with:
Sustained positive emotion
High degree of mental and emotional stability
Constructive integration of the cognitive and emotional systems
Increased synchronization and harmony between the cognitive, emotional and physiological systems
In brief, the research studies summarized here show that different emotional states are associated with different physiological information patterns that are transmitted to the brain and throughout the body. When an individual is under stress or experiencing negative emotions such as frustration, anger and anxiety, heart rhythms become less coherent and more erratic, indicating less synchronization in the reciprocal action that ensues between the parasympathetic and sympathetic branches of the autonomic nervous system. This desynchronization in the ANS, if sustained, taxes the nervous system and bodily organs, impeding the efficient flow of information throughout the body. On the other hand, sustained positive emotions, such as appreciation, love or care, lead to increased heart rhythm coherence, greater synchronization between the
activity of the two branches of the ANS and a shift in ANS balance toward increased parasympathetic activity. Further, we show that when the heart generates a coherent signal, it has a much greater impact on other biological oscillatory systems than when it is generating an incoherent or chaotic signal. When functioning in a coherent mode, the heart pulls other biological oscillators into synchronization with its rhythms, thus leading to entrainment of these systems. The entrainment mode is an example of a physiological state in which there is increased coherence between multiple oscillating systems and also within each system.
In sum, our findings essentially underscore what people have intuitively known for some time: Positive emotions not only feel better subjectively, but tend to increase synchronization of the body’s systems, thereby enhancing energy and enabling us to function with greater efficiency and effectiveness.
The Effects of Emotions on Short-Term Power Spectral Analysis of Heart Rate Variability
Rollin McCraty, PhD, Mike Atkinson, William A. Tiller, PhD, Glen Rein, PhD and Alan D. Watkins, MBBS. American Journal of Cardiology. 1995; 76 (14): 1089-1093.
Key findings: Different emotions affect autonomic nervous system function and balance in measurably different ways. Anger tends to increase sympathetic activity, while appreciation is associated with a relative increase in parasympathetic activity.
Summary: In this study, power spectral density (PSD) analysis of HRV was used to compare autonomic activation and sympathovagal balance in subjects during a 5-minute baseline period, in contrast to a 5-minute period of self-induced anger and a 5-minute period of appreciation. It was found that both anger and appreciation caused an overall increase in autonomic activation, as demonstrated by an increase in power in all frequencies of the HRV power spectrum and in mean heart rate standard deviation.
However, the two emotional states produced different effects on sympathovagal balance. Anger produced a sympathetically dominated power spectrum, whereas appreciation produced a power spectral shift toward increased parasympathetic activity. The technique used to generate a feeling state of appreciation was Freeze-Frame, a new method of intentionally shifting emotional states in the moment through heart focus. The positive shifts in ANS balance that all subjects were able to achieve in this study through using the Freeze-Frame technique may be beneficial in the control of hypertension and in reducing the likelihood of sudden death in patients with congestive heart failure and coronary artery disease.
Figure 8.
The heart rate variability pattern shown in the top graph, characterized by its random, jerky form, is typical of feelings of anger or frustration. Sincere positive feeling states like appreciation (bottom) can result in highly ordered and coherent HRV patterns, generally associated with enhanced cardiovascular function.
Figure 9.
Mean power spectral density analysis of a group of subjects comparing the effects of anger and appreciation on the autonomic nervous system. Anger caused a large increase in the activity of the sympathetic system, which is reflected as increased power in the far left-hand region of the power spectrum. Appreciation, on the other hand, increased the activity in the parasympathetic system, which helps protect the heart.
Cardiac Coherence: A New, Noninvasive Measure of Autonomic Nervous System Order
William A. Tiller, PhD, Rollin McCraty, PhD and Mike Atkinson. Alternative Therapies in Health and Medicine. 1996; 2 (1): 52-65.
Key findings: The experience of sincere positive feeling states may be accompanied by distinct modes of heart function which drive physiological systems into increased coherence. Such shifts are attainable not only under controlled laboratory conditions, but also during real-life stressful situations.
Summary: This study expands the findings discussed in the effects of emotions on short-term power spectral analysis of heart rate variability, above. HRV analysis reveals that sincere feelings of appreciation,as experienced through the Freeze-Frame technique, create positive shifts in ANS function and these shifts are accompanied by distinct modes of cardiac function. While feelings of frustration create a disordered or incoherent HRV waveform, characterized by an irregular, jerky pattern, appreciation produces an ordered sine wavelike pattern in the HRV waveform, indicating increased balance and efficiency in ANS function. It is demonstrated that when the heart is operating in this more ordered mode, frequency locking occurs between the HRV waveform (heart rhythms) and other biological oscillators; this mode of cardiac function is thus referred to as the "entrainment mode."
Figure 10.
The top graphs show an individual’s heart rate variability, pulse transit time and respiration patterns for 10 minutes. At the 300 second mark, the individual Freeze-Framed and all three systems came into entrainment, meaning the patterns are harmonious instead of scattered and out-of-sync. The bottom graphs show the spectrum analysis view of the same data. The left-hand side is the spectral analysis before Freeze-Framing. Notice how each pattern looks quite different from the others. The graphs on the right show how all three systems are entrained at the same frequency after Freeze-Framing.
Another distinct mode of cardiac function, termed the "internal coherence mode," is shown to characterize a positive inner feeling state called "amplified peace," also achieved through using the Freeze-Frame technique. In this state, internal mental and emotional dialogue is largely reduced and the sympathetic and parasympathetic outflow from the brain to the heart appears to be decreased to such a degree that the oscillations in the HRV waveform become nearly zero. In addition, when the heart is functioning in the internal coherence mode, the amplitude spectrum derived from the ECG exhibits a harmonic series (Figure 11).
Figure 11.
The top graph is a typical spectrum analysis of the electrocardiogram (ECG) showing the electrical frequencies generated by the heart when a person experiences frustration. This is called an incoherent spectrum because the frequencies are scattered and disordered. The bottom graph shows the frequency analysis of the ECG during a period when the person is experiencing deep, sincere appreciation. This is called a coherent spectrum because the power is ordered and harmonious.
This study was conducted with the same group of subjects in two different environments: under controlled laboratory conditions and during a normal business day in their workplace. For the workplace portion of the study, subjects wore portable Holter recorders to monitor their ECG and were asked to use the Freeze-Frame technique on at least three occasions when they were feeling stress or out of balance. Results showed that the positive shifts in emotional state, autonomic balance and more coherent modes of cardiac function measured in the laboratory could be attained through the practice of the Freeze-Frame intervention during real-life stressful situations in the workplace, for which the technique is designed.
