The Zolt Sleep Score summarizes the sleep information available for your most recent night. Use the score as a starting point, then open the breakdown to see which measurement moved.
Common questions
- Why is my Sleep Score low even though I slept long enough?
- Why is my Recovery Score low?
- What if my sleep stages are missing?
What appears in the score
Depending on the data available from your connected source, the breakdown can include:
- time asleep;
- sleep efficiency;
- deep sleep;
- REM sleep; and
- awake time during the sleep period.
If a connected platform does not provide a component, do not assume that a displayed zero means the stage did not occur. Check the source data and permissions first.
Where the data comes from
Zolt reads sleep information from the health source you connected. The phone or wearable estimates sleep from its own sensors and software. Zolt receives those measurements and presents them together.
This distinction matters. A Zolt score is only as complete as the source data available for that night. Wearable sleep stages are estimates, not a clinical sleep study.
Read Sleep stages from Apple Watch for the stage labels and their measurement limits.
How to interpret a low score
Open the breakdown and identify the changed component.
| What changed | First check |
|---|---|
| Time asleep | Whether the sleep period is complete and the schedule was shorter than usual |
| Efficiency | Whether the source recorded more awake time or a fragmented sleep period |
| Deep or REM | Whether stage data was present and how it compares with your own recent nights |
| Awake time | Whether the wearable was worn correctly and the sleep period boundaries look right |
| Several components | Whether the source missed part of the night |
Do not chase a single stage percentage after one night. Wearable estimates vary, and sleep architecture changes naturally from night to night.
One night versus the trend
Use one score to understand last night. Use the recent trend to decide whether something has changed.
A run of shorter or more fragmented nights may be useful context for recovery, mood, or training. One unusual reading may simply reflect the night itself or incomplete source data.
If the score looks wrong
- Check the original sleep record in the connected health platform.
- Confirm that the full sleep period is present.
- Confirm that Zolt still has permission to read sleep data.
- Check whether more than one source is writing sleep records.
- Compare the score after the next complete night.
If the source record is correct but Zolt still shows missing information, contact support with the affected date and screenshots of both records.
Related measurements
Use the individual pages when a component, rather than the overall score, is the part you need to understand.