HRV, sleep stages, stress scores — a dietitian's filter on which numbers to actually act on.
A wearable is a very good thermometer and a very bad doctor. It can tell you something changed. It cannot tell you why, and it should never be allowed to tell you how to feel about your morning.
Worth acting on
- Total sleep duration and consistency of bedtime — the highest-leverage numbers on the device.
- Resting heart rate trends across weeks — a rising trend usually precedes the crash you feel later.
- HRV as a seven-day average, never as a single morning score.
- Step count and daily movement, which quietly drives more of your burn than training does.
Mostly noise
- Sleep stage breakdowns — consumer devices estimate these loosely.
- Calorie burn figures, which can be off by a wide margin.
- Daily readiness or stress scores taken as instruction rather than context.
Track what changes your behavior. Ignore what only changes your mood.
One review a week, five minutes, looking at trends — that's the entire discipline. Everything past that is a hobby dressed as health.