This is a bug specific to android devices that is caused when the camera is used. Skype accesses the camera often so it can cause the bug to appear more, it's not Skype itself causing the issue
Test 2. Phone charged at 8AM. KitKat + other apps (Facebook, Instagram, Twitter, Evernote, 4SQ) + normal usage = Next day at 8AM, phone at ~ 50%.
Sure, Skype is not causing the issue (it is limited to Android tho).