Band/Watch - differences in SAA integration/accuracy? How to pick?

Hi there,

I am looking to buy a fittness band / smart watch - solely for use with SAA.
Is there a difference in how well SAA is working with different models/generations?
Is there a difference in accuracy/precision?

Any more detailed knowledge out there?


Am I the only one who’s pondering on this?

You’re not the only one.

A main factor for me would be the battery drain. I’ve got a Garmin Venu 2 Plus and it’s about 15 to 20 % a night. So I will not be able to get all five days on track with a single charge.

Otherwise a wearable is much more precise than the smartphone itself. So as soon as it is a wearable instead of sonar or your smartphone on your mattress, you’re good to go.


Though all those wearables are apparently differ loads when it comes to accuracy of sleep tracking and phases recognition.
And especially the popular mi band seems pretty bad when it comes to recognizing three light sleep phases which are especially bad for the smart alarm…

So I wonder to what extent the different implementation with SAA is even another layer on top of how good which wearable performs…

Hi, Sleep as Android does not use the built-in sleep tracking of any of the watches. We get raw data from the motion sensor (accelerometer) and perform sleep analysis from the raw movement data. So the only thing that matters is how good the accelerometer is, which is pretty high standard in all of the watches, and whether the watch is able to deliver the data continuously for the whole night.

Thanks a lot @jiri-urbandroid !
So you’re saying that even though they’re performing vastly different with their proprietary built-in sleep tracking, they should be performing pretty much the same with SAA?
Have you done any direct comparisons to confirm? That’s interesting!

What about the other sensors as indicated here, HR, HRV,
SpO2 - you’re not involving them in the sleep tracking after all?

Then the most interesting would probably be

  • like you’re saying which ones deliver data continuously
  • Is most energy efficient doing so
  • Can ideally even track with phone not connected over night / in flight mode

Which models would be best for that after all?


The main sensor for sleep tracking is the accelerometer (or sonar on the phone), without it, no sleep analysis can be done.

Other that that, HR is used to aid in discerning awake/asleep state. HRV and SpO2 measures do not affect how sleep phases are detected.

To answer your bullet points:

  • which ones deliver data continuously - this would ideally be all of the supported watches, however watch manufacturers are often flimsy or overly restrictive with regards to long running tasks and some of the supported watches do not send data reliably. This concerns mainly Garmin and Fitbit, I’d say Fitbit is currently most restrictive and I wouldn’t recommend it for sleep tracking.

  • Is most energy efficient doing so - that would be probably Mi Band. Garmin vastly differs in energy efficiency between models (AFAIK the worst being the Forerunner series, while Vivoactive, Fenix are alright).

  • Can ideally even track with phone not connected over night / in flight mode - none of the watches can do it, since the watches have very limited memory and CPU power and cannot hold the data for the whole night, let alone analyze it.