Why did my Nexus 5 battery drain 96% overnight?

[AC Question]

Overnight I have lost 96% of my battery while it was on stand by. For some weird reason the android system was on and kept my device awake for 5h, and along with that the android is seems to have taken a chunk of power too. And theres more, exchange services and gmail have also taken a huge amount. What's even more weird is that didn't have any apps running in the background at all and was fully charged right before I went to sleep.

 

[Rukbat]

That's what I thought this morning, when my battery was critically low from about 70% last night. Then I ran SystemPanelLite and saw that I had left Action Launcher running in the background. (It didn't show up anywhere else.) Killing (and uninstalling - it sucks far too much battery) that stopped the problem.