Hi I know there have been a lot of complaints about iphone batteries but mine has been fine for about 1.5 years but this week has suddenly started draining overnight, despite being almost fully charged when going to bed (so it is draining in about 7 hours, if not quicker, despite not being used). I don't think I am doing anything different. I have the alarm set which obviously doesn't go off because the battery has drained. Any suggestions? Thanks!