Is it possible to use wearable without live bluetooth connection during sleep

Hi, I am looking for ways to lower battery usage on my Wear OS device whilst using sleep as android.

At present, I can see that the Wear OS watch transmits all data over to the phone so at any point I can look at my phone and see what data is being recorded.


Found other threads asking for this as a feature, so guess that answers my question that this is not possible at present!

It’s actually quite possible to use the Wear OS wearable without a live BT connection with Sleep as Android.
All data will be kept on the watch until connection is established again, and then sent at once.
However it’s not straightforward to achieve this - the flow would need to be like this:

  1. start sleep tracking, let the watch connect to Sleep as Android
  2. now you can turn off bluetooth
  3. at some point during the night, you need to turn on bluetooth again (using perhaps some automation app like Tasker)

If you don’t turn on bluetooth again during the night, you won’t get any alarm on your wearable. If you don’t care about this, you can turn on bluetooth when your alarm rings on the phone (but you’ll need to be careful not to dismiss the alarm before the data have transferred over, which can take some time…)

So all in all, this scenario is possible, but not really supported at this moment.

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Thanks for the reply - this is interesting and I will test this to see how this impacts battery, if it leads to a good reduction in battery life I would probably prefer the offline way of doing this.

I have a few questions:

  1. Do you turn bluetooth off on the phone or the watch. (watch would actually be easier)

  2. Also, do you have to use the alarm function for this to work.

  3. So far, I have tried a slight variation to your suggestion and failed: start sleep from watch, wait for app to start on phone (I assume this means they are connected) switch on airplane mode on phone or watch, finish sleep on phone, then reconnect. I assume the issue here is that I need to connect before sleep is ended, i.e. it doesn’t sync once sleep cycle is ended on the watch or phone

  4. Is HR also recorded and then synced later?

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I would be also interested in knowing whether this has a tangible impact on the battery.

  1. On watch, as that would lead to the maximum battery savings. Otherwise the watch would be trying to probe the phone during the night.
  2. Nope, if you don’t use alarm it gets a little simpler.
  3. Exactly - once you finish tracking on the phone, data from the watch won’t sync anymore.
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I will try and feedback on battery life!

Just jumping in here. @jiri-urbandroid, does this process also work for the Galaxy series watches, in particular the Galaxy Watch Active and the Gear S3? I’m working with the REM alerts on these watches now and don’t set the alarm. I would imagine I need Bluetooth on all night for the vibration trigger to be sent to the watch throughout the night, but can you confirm this? AS for this thread, I’m mainly curious if the data is stored in the Tizen OS based watches like in the WearOS watches and can be bulk transferred to the phone in the morning before ending the session on the phone and after reconnecting Bluetooth. Thanks.

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Yes, Tizen based watches have plenty of memory for this so it should be possible (though untested by us).

As for REM alerts, this needs live connection to the phone since the sleep phases are computed there.

I have tried this twice without good results I’m afraid.
The process I followed was:
-I started the sleep on the watch
-I made sure that sleep had started on the phone ( second time I also made sure accelerometer and heart rate data was showing on one)

  • switched watch to airplane mode
  • when woke, switched airplane mode off
  • waited until phone showed accelerometer data etc.
  • then stopped sleep recording.

The armed to be no syncing of the data that wad recorded during the night so I don’t have any phase information offer wakes etc.

Rather unexpectedly, battery drain was also higher, which seems completely counter intuitive!

So, in summary it didn’t work and cause higher battery drain!

I don’t know what I was doing wrong.

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Let’s ask @petr-urbandroid as he might have some insight on what’s going on there (as he wrote the WearOS integration). He’s on a vacation now however so he’ll be available next week…

Thanks @jiri-urbandroid . It would also be great if Petr could look at battery drain after sleep has finished - I posted on: Possible battery drain on Wear OS after closing

(There have been a host of google app updates recently so maybe there is something going on due to that?)

Hi @jiri-urbandroid, @petr-urbandroid - just wondering if you looked into this (both the offline tracking and the battery drain after finishing tracking) and if there was any progress?

Hi @jiri-urbandroid, @petr-urbandroid - just wondering if the was an update on this.

I also looked and noted that the watch app doesn’t have storage permissions. Would that be needed for offline recording?

Wondering what exactly has happened here. @jiri-urbandroid you mentioned you would be looking into this…

To say you were looking at the issue and then completely ignore this thead. Rather unimpressed @jiri-urbandroid.

Wish I had never wasted my money on this app now.