I've been using my iPhone 4 on 4.0.1 since I got it in the summer, and I updated to 4.2.1 yesterday. When I went to go sleep last night, I noticed my phone had 97% battery charge, so I decided not to charge it overnight. When I woke up this morning (slept for 8 hours), the battery was down to 47%!!!!!!!!!!! W T F is all that came out of my mouth. How?!?! I haven't jailbroken it yet or installed anything crazy, and the only app i had open (according to the multitasking window at the bottom) was Photos. What do i do?!?!?