PpgHeart RateBiometrics
Why Your Morning Coffee Confuses Your Sleep Tracker: Caffeine, Biometrics, and the False Recovery Signal
Caffeine changes your biometrics in ways that look like recovery to a wearable. Higher HRV, elevated resting heart rate, and altered sleep architecture produce a readiness score that says you are rested while your body metabolizes a stimulant. Here is how the blind spot works and what wearables could do about it.
James Hoffmann Jun 17, 2026 · 1 min read