Completely normal — do not report
- A night you did not wear the device. The commonest gap there is.
- A charging night. Same thing.
- A day you logged nothing. Expected.
- Your first two weeks looking thin. Baselines need history.
- A measurement your device does not make. No Apple Watch reports time to sleep. No Polar reports naps.
- Data appearing a day late. Some sources sync slowly.
Expected, and worth mentioning if it persists
- A source that has not updated in several days while you have been using the device. Check the connection first.
- Sleep recorded but no HRV, repeatedly. May mean the device is not being worn tightly enough.
- Regular short nights the app treats as full ones. Worth telling us if you think the boundaries are wrong.
Probably a bug — please report
- A gap on a day you definitely wore the device and it definitely synced.
- Data appearing on the wrong day, especially around midnight.
- A figure that cannot be right — a resting heart rate of 30, a night of 14 hours you did not have.
- Something that used to work and stopped, with no change at your end.
- A number that disagrees with itself in two places in the app.
Why we want the gaps as much as the data
An app that only works for people with unbroken data is an app that works for almost nobody. We need to know how often gaps happen, what causes them, and whether the calculations behave sensibly across them — whether a Capacity figure after a missing night is honest about its uncertainty, or quietly pretends.So please do not wear a device more to reduce gaps. The gaps are part of the
measurement.