9 to 5 sucks ass.
You gotta listen to your body and take that powernap when you can (already made a previous comment about how the human body isn't built to do strict wake-sleep cycles, it's natural to have 2 separate sleeps in the same night, and historically people from early morning to noon since the sun is too harsh by then). I generally found taking a 15 minute nap after a meal is enough to get me through the rest of the day. Though it's insane that corpos expect anything more than 60% effort after 2pm when most have been up since 6am.
Take your hours back, they won't give it back to you.