Noticed my battery was nearly dead only halfway through the day, so had a look at what was the culprit. Insane usage from Fitbit app, which had only just received an update with some fancy bells and whistles with it. Will be watching it closely because that is unacceptable.
Best AnswerAfter updates (not just Fitbit, but a lot of other apps to) it is often advised to reboot the phone.
Had the same problem on my Android phone, but after reboot, never happend again.
Yes I get this now and then on Android too. The Fitbit app will keep the phone awake. Luckily I often catch it before it causes too many problems.