HRV SDNN
HRV SDNN is a health-education page for Yuelu Body Age. HRV SDNN reflects heartbeat-interval variation and relates to stress and recovery; it is no longer used directly by the current Yuelu Body Age model. Read it as trend context rather than a judgment from one day.
Role in Body Age
HRV SDNN is kept for older app entry points and user education. The current Yuelu Body Age model uses the split signals shown on the related pages, which makes the result easier to explain.
Current Yuelu Method
| Field | Current rule |
|---|---|
| Data source | Apple Health heartRateVariabilitySDNN |
| Lookback window | Available recent samples in Apple Health |
| Metric | SDNN in milliseconds |
| Missing-data rule | Not required for the current Body Age main result |
Interpret HRV against your own baseline. Poor sleep, alcohol, stress, fever, or excessive training can reduce short-term HRV.
How to Improve
- Use the related current pages as the practical guide.
- Compare trends across several days or weeks.
- Check Apple Health permissions and Apple Watch recording quality.
- Prioritize sleep, sustainable activity, and recovery before chasing a score.
When Data Is Missing
Check Apple Health permissions, source priority, Apple Watch battery and wear time, and whether the relevant samples were recorded recently.
Rule Basis
- Yuelu Body Age follows the current in-product calculation rules for sleep, activity, and fitness signals.
- Data is read from authorized Apple Health and Apple Watch samples when permission is granted.
- Interpretation is for wellness education and product explanation, not medical diagnosis.
Disclaimer
This material is for health education and product explanation only. It is not medical diagnosis or treatment advice. Consult a qualified clinician for persistent symptoms or health concerns.