iPhone 4 acting as if it's in use when not.

Hi, I'm new here, I apologize if this is a common or repeat topic, I checked through a few pages and didn't see one exactly matching my problem.

The issue I'm having is all of a sudden my iPhone 4 batery is draining overnight, acting like the phone is being used when it's not. The past 3 days I've woken up with a dead battery. I went to sleep with the phone at 30% to 40% and 5 to 6 hours usage and when plug the phone in to charge in the morning and check the usage it's all the way up to 9 or 10 hours. I have all background apps shut off, so I have no idea why it's doing this.

As a test I put the phone in Airplane mode last nigh for a few hours before I went to bed. The battery did stay constant at 34% for those 2 hours it was in Airplane mode, but I don't want to do this everynight as what if I recieve an emergency call and can't get it because of that? So if turning on Airplane mode stopped this then clearly something IS draining the battery, any suggestion on what it might be or what I can do to stop this?

 

I'll only bump this once as I really hope for an answer. It won't stop happening, went to bed last night with 47% battery and 5 1/2 hours of use, woke up with 22% battery and 12 hours use. What the heck could be doing this?