Autonomic Nervous System (ANS)

The Autonomic Nervous System (ANS) is the division of the peripheral nervous system that controls involuntary physiological processes including heart rate, blood pressure, respiration, digestion, and temperature regulation. The ANS operates largely below the level of conscious awareness and is divided into two primary branches: the sympathetic nervous system and the parasympathetic nervous system.

The sympathetic nervous system activates the body's "fight-or-flight" response, increasing heart rate, blood pressure, and respiratory rate while diverting blood to muscles. The parasympathetic nervous system promotes "rest-and-digest" functions, slowing heart rate, lowering blood pressure, and supporting recovery. Healthy autonomic function involves a dynamic balance between these two branches that adapts to the body's changing needs.

Heart rate variability (HRV) is the primary non-invasive measure of autonomic nervous system function. Higher HRV indicates better autonomic balance and adaptability, while reduced HRV suggests autonomic dysfunction. Contactless vitals technology using rPPG can assess autonomic function through HRV metrics like RMSSD (reflecting parasympathetic activity) and SDNN (reflecting overall autonomic variability), providing insights into stress, recovery, and cardiovascular health.