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SDNN Measurement

Meaning

SDNN (Standard Deviation of the Normal-to-Normal intervals) Measurement is a primary time-domain metric derived from Heart Rate Variability (HRV) analysis, quantifying the overall variability in the time intervals between consecutive heartbeats. Clinically, it serves as a robust indicator of the total autonomic nervous system (ANS) activity and is widely used to assess physiological resilience, stress load, and the body’s capacity for adaptation. A higher SDNN value generally correlates with a healthier, more adaptable ANS profile.