Getting back to baseline
After a cold or the flu, your numbers take a while to come back. ZONAL checks two things: whether you're back on Today while you're sick, and how fast you bounced back once the illness ended.
While you're sick: the Back to baseline card
While a sick period is open, Today compares this morning's resting HR and HRV with your healthy normal (your last 28 healthy days). A morning counts as back when both are inside these margins:
| Signal | Counts as back when | Setting |
|---|---|---|
| Resting HR | No more than 1.5 bpm above your normal | Back: resting HR within (bpm) |
| HRV | No more than 3 ms below your normal | Back: HRV within (ms) |
| Mornings | 2 back mornings in a row | Mornings in a row |
The card shows a dot for each morning, like "1 of 2 mornings back". When you're there, it says "You look back to normal." Tap I'm recovered to end the sick period. Until you're back, the morning call stays Swap (unless you turned Swap while sick off).
After you're sick: Bouncing back
A week or month that's short on healthy mornings because you were sick gets a sick report in Reports instead of an empty page. It compares you with your healthy normal from the 28 days before you got sick, and has a Bouncing back section.
You count as back on the first 3 mornings in a row after the illness where your average recovery and average HRV are both within one standard deviation of that normal (your usual day-to-day swing). The report then says how many days that took, like "Back to your normal recovery 4 days after you got better".
If you're not there yet, it shows where you are instead, like "Still below your normal: HRV 48 ms vs 55". If the sick period hasn't ended, it says you were still sick at the end of the week or month.
Good to know. The report also shows each illness signal at its worst (highest resting HR, lowest HRV, skin temperature or breathing rate, lowest recovery) and how you slept. Your sick notes are never shown.
Questions
Why does Today say I'm back but the report says I'm not?
They use different checks. Today needs 2 mornings in a row inside a small resting HR and HRV margin. The report needs 3 mornings averaging within your usual swing for recovery and HRV, counted after the sick period ends.
Can I change what counts as back on Today?
Yes. The margins and the number of mornings are in Advanced settings, under Sick days. See Settings.
Do travel days count toward bouncing back?
No. With travel days left out of your normals, those mornings are skipped, just like sick days.