An important point is that the state of coherence is both psychologically and physiologically distinct from the state achieved through most techniques for relaxation. At the physiological level, relaxation is characterized by an overall reduction in autonomic outflow (resulting in lower HRV) and a shift in ANS (Autonomic Nervous System) balance towards increased parasympathetic activity.
Coherence is also associated with a relative increase in parasympathetic activity, thus encompassing a key element of the relaxation response, but is physiologically distinct from relaxation in that the system oscillates at its natural resonant frequency and there is increased harmony and synchronization in nervous system and heart–brain dynamics.
This important difference between the two states is reflected most clearly in their respective HRV power spectra (see figure and explanation below). Furthermore, unlike relaxation, the coherence state does not necessarily involve a lowering of heart rate, or a change in the amount of HRV, but rather is primarily marked by a change in the heart rhythm pattern.
The two graphs on the left show typical heart rate variability (heart rhythm) patterns during states of relaxation and coherence. To the right are shown the HRV power spectral density plots of the heart rhythm patterns at left. Relaxation produces a high-frequency, low-amplitude heart rhythm, indicating reduced autonomic outflow. Increased power in the high frequency band of the HRV power spectrum is observed, reflecting increased parasympathetic activity (the “relaxation response”). In contrast, the coherence state, activated by sustained positive emotions, is associated with a highly ordered, smooth, sine-wave-like heart rhythm pattern.
Unlike relaxation, coherence does not necessarily involve a reduction in HRV, and may at times even produce an increase in HRV relative to a baseline state. As can be seen in the corresponding power spectrum, coherence is marked by an unusually large, narrow peak in the low frequency band, centered around 0.1 hertz (note the significant power scale difference between the spectra for coherence and relaxation). This large, characteristic spectral peak is indicative of the system-wide resonance and synchronization that occurs during the coherence state.
Not only are there fundamental physiological differences between relaxation and coherence, but the psychological characteristics of these states are also quite different. Relaxation is a low-energy state in which the individual rests both the body and mind, typically disengaging from cognitive and emotional processes. In contrast, coherence generally involves the active engagement of positive emotions. Psychologically, coherence is experienced as a calm, balanced, yet energized and responsive state that is conducive to everyday functioning and interaction, including the performance of tasks requiring mental acuity, focus, problem-solving, and decision-making, as well as physical activity and coordination.