How much battery of polar verity sense usually gets used per night when sleep tracking?

Sleep as Android Q&A
1

The polar verity sense is rated for 20hrs battery, does this mean if I sleep track for 8hrs with polar sense, will only 12hrs of battery will be left?

2

Did you ever find out?

3

I just got a polar sense, and it uses about 40% battery per night so it lasts for 2 nights before needing to be charged.