Shutdown, within the depth-psychology and somatic-trauma corpus, designates a specific organismic state of profound physiological withdrawal activated when all other defensive strategies have failed. The term is not employed casually as a metaphor for emotional unavailability; rather, it names a precisely located neurobiological event governed primarily by the dorsal vagal branch of the parasympathetic nervous system — the phylogenetically oldest pathway in the polyvagal hierarchy. Porges supplies the foundational neurophysiological scaffolding, identifying shutdown as the vegetative vagus’s ‘last resort’ response to inescapable threat, characterized by decreased heart rate, hypotension, and potential loss of consciousness. Levine extends this framework clinically, demonstrating that chronic posttraumatic suffering tends to gravitate toward shutdown over time, manifesting as alexithymia, depression, and radical attenuation of social engagement. Ogden’s sensorimotor perspective distinguishes shutdown from the freeze response — an important differential: freeze is sympathetically hyperaroused, while shutdown is dorsal-vagally hypoaroused, producing flaccid rather than rigid musculature. Dana and Rothschild further refine the clinical picture, with Rothschild offering the instructive computer-crash analogy to clarify that shutdown arises from overwhelming excess rather than energetic deficit. Across these authors, the central tension is therapeutic: shutdown renders subjects physiologically inaccessible to the relational and linguistic interventions that constitute conventional psychotherapy, making somatic, bottom-up approaches indispensable.