What 90 Days Of HRV Data Taught Me About Stress I Thought I Was Managing

Why I Started Pointing a Sensor at My Stress

I thought I was pretty good at managing stress. Classic founder-dev story. I train, I sleep, I eat real food most of the time. I meditate when apps guilt-trip me enough.

But my body kept disagreeing. Random brain fog days. Workouts that felt heavier than they should. Waking up tired even after eight hours. The usual “I guess I am just getting older” excuse started to feel lazy.

I wanted a number. Something that could call my bluff when I said “I’m fine.” Heart Rate Variability looked like the right kind of annoying honesty.

The Setup: One Simple Daily Measurement

I kept it boring on purpose. If a tracking workflow is annoying, I drop it after ten days. I wanted ninety.

Hardware and workflow:

• Device: Oura ring, but I cross-checked with a Polar H10 + HRV4Training app for the first two weeks to make sure the trend matched. It did, within a few ms.
• Metric: Morning RMSSD HRV, averaged across the night. I ignored the proprietary “Readiness Score” and stuck to raw-ish numbers.
• Time frame: 90 consecutive days. No gaps.
• Context notes: I logged: training load (RPE 1–10), alcohol (units), late screens (yes/no), intense coding days (yes/no), coaching practice, social stuff, travel.

My goal was not lab-grade science. I wanted repeatable patterns I could actually use.