Glossary /
Polyvagal Theory
Stephen Porges's framework describing how the vagus nerve regulates safety, connection, and the stress response.
What it is
Polyvagal theory, proposed by neuroscientist Stephen Porges in 1994, divides the autonomic nervous system into three evolutionary layers: a ventral vagal branch that supports social engagement and calm, a sympathetic branch that mobilizes fight-or-flight, and a dorsal vagal branch that triggers shutdown or freeze. The body moves between these states constantly, often without conscious awareness.
Why it matters
The theory is debated in academic neuroscience — the precise anatomy is messier than the original model — but it remains useful as a practical map. It explains why a calm voice, eye contact, slow exhales, and humming can shift you out of anxiety in a way that arguing with your thoughts cannot. Therapists working with trauma rely on it heavily because it reframes “willpower” failures as nervous-system states you can learn to influence.