IPhone loses charge overnight.a lot of charge. Why?

My iPhone 4S was on 5.1.1 but i did restore the software last week and used a backup to also restore the files.

Since then I have been losing about 35-40% of my battery overnight, I'm a very power-conscious person, I only use wi-fi, 3g when i need to and i usually keep everything off except data, notifications are to a minimum and location services are off as well as brightness being as low as possible.

What is going on?
Any help is appreciated

Just using your iPhone a lot will reduce battery life too. And overnight has a lot of hours so… It will run.

You've got a dud battery. If it's still under contract, ask for a new one. If not, you'll need to buy one.

Did you upgrade via a cable to the computer or by going in to settings and clicking on check for software update. A lot of people have been complaining that the phone based update is causing major battery issues. My advice would be to back it up. Reset it to factory settings on the phone, then update via iTunes only. Then restore your data.

Another fix was to reset all settings. This made a major difference with me too. Good luck.
Settings > General > Reset > Reset All Settings (do not click Erase all content and settings). This will just set up your settings again, and apparently fixed the glitch with the update for some people.

Background apps can also be a cause make sure that all your background are off.

sometimes batteries need to be calibrated after a month. To do this you must complete me drain your battery and charger to 100 percent that should work