How Does Breathing Through the Heart Sync Two Brains?

Kelly McGonigal says breathing through the heart puts awareness in the chest and can drop a person into a state where two people's hearts start beating in a similar rhythm and their brains start affecting each other.

The brain monitors signals from the heart area: the skin of the chest, the muscles in the chest, the rhythms of the heart, and blood pressure. The body always tracks the signals so the heart does not stop, but the part of the brain that processes sensory information so a person feels it does not always pay attention. Research finds that when more information comes from that sensory system, the sense of self feels located in the chest rather than behind the forehead and the eyes. Most people experience the world as if they are behind the forehead and the eyes and the world revolves around them. When the sense of self drops to the chest, people describe being more open, a 360 awareness of the world, more connection, and softer boundaries with the world. Imagining breathing through the heart was one exercise taught in the compassion training, and it puts awareness in the chest.

Once a person is in the state, bodies and brains start synchronizing. In a conversation where both people feel more connected, one heart starts beating in a rhythm similar to the other, and each brain communicates with the other brain and affects its activity. Scientific papers draw head number one and head number two with crisscross nodes that bind the brains together. The pair functions as a connected system, felt as bonding, rapport, and closeness.