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Autonomic Tone Shift

Meaning

Autonomic Tone Shift refers to a sustained, measurable change in the relative balance between the sympathetic and parasympathetic branches of the Autonomic Nervous System (ANS). A shift toward sympathetic dominance, often termed ‘fight-or-flight,’ indicates chronic physiological stress, negatively impacting digestion, sleep, and hormonal regulation. Conversely, a shift toward parasympathetic predominance, the ‘rest-and-digest’ state, signifies improved recovery, reduced allostatic load, and enhanced physiological equilibrium. Clinicians monitor heart rate variability (HRV) as a primary biomarker to quantify this essential physiological balance.