Autonomic nervous system regulation occupies a foundational position across the depth-psychology corpus, functioning not merely as a physiological backdrop but as the primary substrate upon which emotional life, social behavior, developmental trajectory, and therapeutic change are organized. Porges’s Polyvagal Theory furnishes the most elaborated account, reconceiving the ANS as a phylogenetically layered hierarchy in which vagal tone, the vagal brake, and the social engagement system jointly determine the organism’s capacity for safety, connection, and self-soothing. His framework shifts attention from the classical sympathetic-parasympathetic duality toward a tripartite architecture that includes the evolutionarily ancient dorsal vagal shutdown system. Craig approaches ANS regulation from the interoceptive pathway, mapping ascending lamina I projections and challenging static homeostatic set-point models in favor of dynamic, multidimensional balancing across effectors. Schore situates ANS regulation within the orbitofrontal cortex’s developmental role, tying early relational experience to long-term autonomic patterning. Dana, Ogden, and Levine translate these neurobiological findings into clinical practice — emphasizing co-regulation, the window of tolerance, and bottom-up somatic intervention as pathways for restoring regulatory capacity disrupted by trauma. The central tension across the corpus concerns directionality: whether top-down cortical governance or bottom-up visceral signaling holds therapeutic priority, and how the two must ultimately be integrated.