Heart rate normally varies with the respiratory cycle, typically increasing during inhalation and decreasing during exhalation.

This page isolates one claim from the wider argument of The Human OS Manual.

The classification describes the evidence supporting this claim, not the Human OS framework as a whole.

Lehrer and Gevirtz describe respiratory sinus arrhythmia as a normal cardiorespiratory oscillation in which heart rate changes across inhalation and exhalation and discuss its relationship to baroreflex and vagal mechanisms.

Respiratory sinus arrhythmia is not a direct meter of emotional safety, and a single breathing-linked heart-rate pattern does not diagnose autonomic health.

The book uses RSA to make breath-heart coupling legible without treating HRV or respiratory phase as a complete reading of state.

Broad, mature principles of human biology, behavior, or regulation supported across a substantial body of research.

Sources are listed according to the role they play in this claim. One source may provide direct support, another may explain a mechanism, establish a limitation, or prevent an interpretation from becoming broader than the evidence allows.

The printed book preserves the claim inside the argument that gives it meaning. These references connect the current digital record to the first-edition evidence trail.

This claim connects to the following parts of the Human OS architecture. The module labels locate the claim inside the framework; they do not imply that the research source validates the architecture itself.