First of all, restart your device. It solves a lot of issues. Your phone will work better if you restart it once per week.
Second, go to system settings -> battery -> powermaster -> auto-start manager and prevent all the apps to auto start that you don't need a notification from.
After this go to system settings -> advanced -> Mobile Manager -> Memory cleaner -> Turn on Super Clean mode -> enter app list and uncheck any app that you must get notifications from -> go back -> open recent apps overview and press clear all.
Restart your phone.
If you notice that you battery life has improved, then you have a battery draining app among the apps that are no longer allowed to start by itself.
If the tricks above doesn't work, then please put your phone in flight mode when you go to bed. If you have lost more than a couple of percent after 8h sleep, then there might be a bug in the system that we have to investigate.
