Hi guys. As entitled, I am currently experiencing a prob with my iPhone 5 battery. Whenever I go to sleep I would turn my airplane mode on and leave my phone there until next morning. Since 3 days ago, my phone has been draining up to 40% per night. I.e. 80% --> 40% overnight. Would appreciate help from anyone here... I was told by my friend to charge my iPhone overnight to 'reboot' the battery. Doubting the credibility of his statement, so am asking here first. Anyone can kindly give me advices, thanks a lot! It's really urgent as my days are pretty long and this can be very problematic in the long run. Thank you in advance!