Missing HRV: no reading does not mean zero
A missing HRV value describes a gap in the data. It is not a measurement of zero and does not establish poor recovery. Before using it to explain a training decision, check whether a recent measurement exists and whether the app interpreting it can access that record.
Three different situations
Distinguish a recorded low value, an older value and a missing record. A low reading can be compared with your previous measurements. An older record belongs to another time. A missing entry contains no measurement for that moment at all. An app should make these differences clear rather than show all three as a bad score.
What to inspect in Apple Health
Open heart rate variability in Apple Health and look at the individual entries. Check the date, time and source. Apple stores HRV as SDNN, documented as the data type heartRateVariabilitySDNN. Other devices or apps sometimes use RMSSD, a differently calculated metric, so their numbers are not directly comparable. More on that in SDNN vs RMSSD.
Locate the gap
If the companion app has a reading but Health does not, check the transfer. If Health has it but LeibFit does not, check read access for heart rate variability. If there is no overnight reading anywhere, look at recording and fit. Wearing a watch overnight does not guarantee that an HRV measurement was taken during that time. Missing Apple Health data walks through the whole path step by step.
What LeibFit shows when HRV is missing
For each night, LeibFit takes the HRV readings between falling asleep and waking up and turns them into one value. If there is no reading in that window, the app scores recovery from the night's other signals, resting heart rate and sleep. It does not fill in a substitute HRV value. On the Today screen you then see how many of the night's signals came in. HRV is marked as missing, with a note that your readiness still works but is a little rougher.
If the whole night has not arrived yet, LeibFit shows the latest available data and says when it is from, for example "As of last night". That way you can always tell whether you are looking at a current, an older or an incomplete value. What Apple Watch records as HRV overnight is explained in What Apple Watch measures as HRV at night.
Keep training context in view
A single sensor value is not a training plan. Look at data availability, trends and your actual workload over the last few days together. If HRV is missing often, check how snugly the watch sits at night. A missing reading is not a health finding.
Frequently asked questions
Is missing HRV worse than low HRV?
They cannot be compared. A missing entry provides no measurement; a low entry provides a value that can be compared with your own baseline.
Should I estimate or add the missing value?
Do not invent a measurement. An estimated value becomes part of your series and distorts the trend that later readings are compared against. Record the gap and check its cause instead.
Sources
- Apple Developer: heartRateVariabilitySDNN
- Apple Support: Manage health data on your iPhone