Why does battery drain to 0% overnight?

[Windows Central Question]

Since installing the new Windows 10 anniversary update, my battery drains from 100% to 0% while in sleep mode overnight. The battery life has not changed during the day, when I am actively using it. Any ideas why / how I can stop this?

 

[anon(2523636)]

If you go into Settings > System > Battery > Battery Usage By App and look at what is using your battery. If you tap each entry you will see whether the activity is the app in active use or background tasks, and have the chance to turn the background use off if required.