System and method for synchronizing the heart rate variability cycle with the breathing cycle

The invention consists of a method and system for achieving coherence of heart rate variability by synchronizing the heart rate variability cycle to the breathing cycle and by consciously synchronizing the breathing cycle with an external reference that is closely aligned with the frequency of the natural heart rate variability cycle. Various means of representing the cycle of the external reference are provided including visual, audible, and sensory indicators. An instructive method is provided that teaches the subject to consciously synchronize their inhalation with the positive going aspect of the external reference cycle and their exhalation with the negative going aspect of the external reference cycle.