My iPhone 5's battery life has been greatly decreased since I updated to iOS7?

So when I updated to iOS7 my phone has been losing like 10-15% overnight. Is this normal? If it's not, is it my battery and should I get a new one?

No it's not normal lol… My sister has an iphone 5 and she upgraded to ios7 with no problems

Try restoring or going to the apple store and talk to one of the staff, they should be able to help you or even replace your phone (if your still under warranty or if it is a fault in the phone)

Try restore to previous system, and perform the update once again. Pay attention to any additional softs\proccesses.

Something can't' be right, look at it this way, the more stuff you constantly run then the more power it takes. Dim the brightness, you don't need it fully bright, turn off location services unless you are traveling or using maps, turn off bluetooth if not using, background updates should be off, etc.