How does my phone know, when I am in the deep sleep? - Sleep as Android

We use a method called sleep actigraphy and there are several scientific papers which show that it is not as precise as PSG but still provides reasonable data and more over it is more convenient for the user. The phone has an accelerometer sensor build in which is very sensitive and if placed in your bed we have a record of your movement over the nigh. In deep sleep your muscular movements are suppressed (otherwise you would be running or jumping around according to your dreams :)) and thus in this phase the sleep graph gets nearly flat. This is in short how we measure your sleep phases, for more details refer to How it works.

This is a companion discussion topic for the original entry at

What happens if you often move around in your sleep according to the dreams you are having? Examples: punching, kicking, “running”, generally talking, etc.

Hello @Screaming.Opossum… this happens mostly in the REM phase of your sleep and we expect activity to happen in that phase. Those activities would need to be so intense that we would consider them as awake… but even in this case you can adjust the awake detection thresholds in Settings > Sleep tracking > Awake

Hi. What if I consistently have <15% of deep sleep? Is this an issue with sensitivity?

Hi, which sensor do you use for sleep tracking?

I use Mi Band 5 with Notify App. The sensor setting is set to accelerometer.