It seems like my phone isn't going to sleep like it should and Android OS keeps running. It went from 100% to 61% when it wasn't even in use. Any ideas?
Can you post some screenshots of the Battery graph and stats? Does it show that it's staying awake overnight? Are there any particular apps that are using a disproportionate amount of battery?
Does it persist after a reboot? Also, tap on the Android OS entry, and also tap on the battery graph itself, and show us the data on those screens. It'd be interesting to see if your phone is being kept awake the whole time.
Did you look through the guide I linked above, and try some of those tips? Like turning off Location Reporting, for example?
The unfortunate thing about KitKat is that we can no longer use wakelock detecting apps to tell us what processes are keeping the device awake--unless the device is rooted.