Phone is awake without even any internet connection

I can understand when there's an internet connection most of the apps will try to sync their data and all but, what could a phone possibly do for hours, without any internet connection, without any low signal to keep the phone awake? If phones had hard drives I would say defragmanting etc but no... And it's "Android OS" who's responsible for this.


See that loooong bar there? It just kept happening like that until I rebooted the phone, cleared the RAM and the system cache. And like I said, %90 of the time the internet was off. Signal was pretty good.
"(Uyanık" means "Awake by the way)

So, what's the problem here?