What to expect when you first open Underbark
What you see on day one depends on the history available for comparison, not on how long the app has been installed.
Direct answer
What you see on your first day depends on the relevant history available for comparison, not on how long Underbark has been installed. If little relevant history is available, some results stay unavailable until enough records exist.
Your existing history is the starting point
Underbark does not begin counting from the day you install it. Earlier comparable records can contribute to the personal comparison you see.
This is why two people can install Underbark on the same day and see different things. Someone who has worn an Apple Watch to bed for months may see a personal comparison quickly. Someone who has just started wearing one, or who has recorded few nights, may see fewer results at first.
Why some results still need more records
A personal comparison needs enough earlier readings of the same kind to compare against. Having a long record history in general does not guarantee that every individual reading has enough history behind it. A metric your Watch never recorded, or one your model does not support, has no history to draw on regardless of how long you have worn the device.
Some comparisons also depend on the kind of record rather than the amount. Bedtime consistency, for example, needs a number of bedtime records before the current app will compare against them. Read more about what each part of a night contributes in what a sleep score can and cannot explain.
An empty or calibrating result is a software state
If no input can contribute, the current app can display 0, Calibrating. This is a software calibration state, not a physiological zero or an adverse health finding. It means the app does not yet have a usable scored input.
Underbark keeps an unavailable input unknown rather than substituting a zero or estimating a value. Seeing a result described as unavailable tells you something about the records, not about your recovery or your health.
Early results can move, and that is expected
As more comparable records accumulate, what is typical for you becomes better described, so an early result can shift. A change shortly after installing does not mean an earlier result was wrong or that something about your body changed. It means the comparison had less to work with before.
What to check if you expected to see more
If Underbark shows less than you expected on the first days, these checks may help you understand what is available:
- Look in Apple Health for the records you expected, and how far back they go.
- Note which device or app supplied those records, and whether that source records the detail you are looking for.
- Check whether your Watch is set to track sleep, if overnight results are the ones missing.
- Allow more nights to accumulate if the history behind a particular reading is short.
These checks can help you see what Apple Health holds. They cannot create a record that was never captured, and they cannot guarantee a complete future night.
Know where this stops
If a reading concerns you or you need help deciding what is safe, seek advice from a qualified health professional. For help understanding Underbark's behavior, visit the support page.