A Therapy Target

Because so much traffic runs along the vagus nerve, doctors can use it as a dial. Vagus nerve stimulation — small implanted devices that send gentle pulses — is FDA-approved for depression and epilepsy that no longer respond to medication.

You can nudge the same system without surgery. Slow, deep breathing and a splash of cold water on the face both switch on the vagus nerve's calming, anti-inflammatory pathways.