Cardiac coherence is first introduced in The 7 Skills to impress™ Part 2, Skill 2: Manage Your State.
It is a calm, rhythmic state in which your breathing and heart rate are in sync, creating a steady “heart–brain” connection. When you breathe slowly and evenly, about five to six breaths per minute, your heart rate smooths into a coherent pattern.
This coherence signals safety to your brain, reducing stress hormones and improving focus, composure, and emotional control.