Bio OS

Root Mean Square of Successive Differences between adjacent RR intervals, in milliseconds. Reflects parasympathetic nervous system activity. Higher = more adaptive autonomic regulation. Typical camera-derived range: 15–70 ms.

Standard deviation of RR intervals divided by mean RR interval. Measures rhythmic consistency independent of heart rate. Lower values (0.03–0.10) indicate a very stable rhythm; values above 0.25 suggest irregular beats or measurement noise.

How completely the heart rate has returned toward its mean after the highest recorded beat in this session. 0 % = HR still at its peak; 100 % = fully recovered to baseline or below.

Linear regression slope of RR intervals over the measurement window. Negative = heart rate gradually slowing (relaxation response). Positive = HR accelerating (rising arousal or activity).

Second derivative of RR intervals — the rate of change of the trend. Positive = HR is speeding up faster than before. Negative = the rate of change is decelerating, even if HR is still rising.

Composite of rising HR and elevated breathing rate. High values indicate a fight-or-flight activation pattern in the autonomic nervous system.

Inverse of CSI plus energy reserve. High score = low HR variability irregularity, slow stable breathing, and ample cardiovascular headroom — the signature of restful alertness.

Blend of energy level and inverse stress. Peaks when HR is moderate, rhythm is stable, and stress is low — consistent with sustained attentional effort without overarousal.

Rises with HR elevation above resting baseline and higher breathing rate. Distinguishable from alarm by the absence of extreme stress scores — it is positive arousal rather than threat response.

Increases when energy is depleted and stress is chronically elevated. Reflects the physiological cost of prolonged effort: reduced HRV, elevated HR at rest, and slow recovery.

The optimal performance state: high focus, moderate relaxation, and HR slightly above resting without alarm. Appears when you are fully engaged but not overwhelmed — the zone.