Coherence

In the biofeedback literature, coherence refers to a measurable state in which heart rhythm, breathing, and brainwave patterns are synchronized at a resonant frequency (typically around 0.1 Hz, or about 6 breaths per minute). The state is associated with reduced stress, improved cognitive performance, and better emotional regulation.

HeartMath popularized coherence as a trainable skill: by breathing at a specific cadence while watching real-time HRV feedback, you can learn to enter the state on demand. The published research base is real, particularly in stress and performance contexts.

Coherence training is one of the older and better-validated forms of consumer biofeedback. It's also one of the few wellness practices that requires almost no equipment — though devices like the HeartMath Inner Balance make the feedback loop explicit and the practice easier to learn.