Is there a way to make my phone change it's behavior depending on the time of day? For example, from 8 to 5 it's programmed for the things that I need for work and from 5pm to 8AM it's theme is for personal use?
Toggle Settings is the tool I use to change every setting imaginable at specific days/times/events etc.
That's assuming by "Theme" you mean "Settings Profile". If you mean Theme as in icons, background image, etc. then I don't know of anything that can do that.