Autonomic Nervous System

Breath control directly modulates the autonomic nervous system, CO2 tolerance, and prefrontal cortex activity. Here's the evidence on breathing techniques that improve focus, reduce stress reactivity, and recover cognitive capacity between deep work sessions.

Heart rate variability is the most actionable biometric a developer can track. Here's what HRV actually measures, which devices work, how to interpret your trends, and how to use the data to make smarter decisions about training, sprint work, and recovery.