It is strange that you'd find it updating when you wake up, but I can tell you with 100% certainty that the updater isn't messing with your network settings because it doesn't have access to modify that setting.
According to Android docs:
Android also attempts to choose a time when the users aren't using their devices at all.
My best guess is that the updater downloads the update, schedules it with the system, the system waits until you're not using your phone and the battery is charged enough, then it applies the update. You just get to see the end of the updating process when you have to restart your phone (or you set it up to restart itself automatically), and you just see the last part after logging in.