Polyvagal theory, developed by Dr. Stephen Porges in 1994, expands the traditional two-state model of the nervous system (sympathetic = fight/flight, parasympathetic = rest/digest) into a three-state hierarchy: (1) ventral vagal (safety, social engagement), (2) sympathetic (mobilization, fight/flight), and (3) dorsal vagal (shutdown, freeze, collapse).
The ventral vagal state is the optimal state for daily life — you feel safe, connected, curious, and creative. The sympathetic state mobilizes energy for action — useful for exercise, deadlines, and genuine threats, but exhausting if chronic. The dorsal vagal state is a last-resort survival response — it causes dissociation, numbness, fatigue, and depression when activated chronically.
Breathing exercises primarily work by shifting from sympathetic to ventral vagal — activating the 'smart vagus' that promotes safety and connection rather than the primitive dorsal vagus. Slow breathing with an extended exhale, humming (bhramari), and social co-regulation (breathing with others) are the most effective polyvagal interventions. This explains why breathwork feels not just calming but also connecting.