Anxiety manifests physically because the nervous system generates bodily sensations before conscious awareness registers them. The autonomic response activates first, producing changes in heart rate, breathing, muscle tension, and digestion. These physical states then influence thoughts and emotions rather than the reverse.
The autonomic nervous system operates through learned associations between environmental cues and past events. When similar patterns appear in the present, the system activates the same physiological responses that occurred during previous threatening situations. This creates a feedback loop where heightened arousal generates more scanning behavior, which in turn reinforces the sense of danger.
Chronic activation depletes the body's resources over time. The system remains in a state of readiness that was originally a response to specific circumstances but has become a default mode of operation. Neural pathways that fire repeatedly become strengthened, making the activated state increasingly automatic and difficult to interrupt through conscious effort alone.