An often-missing ingredient in our fitness programs is adequate sleep. I find it odd that we glorify not sleeping as a measure of our importance—who has time to sleep with all this crucial stuff that depends on us? And then we hit the sugar/caffeine/adrenaline downward spiral.
I vote for an upward spiral. Of course we all have work to do. Working out can improve our sleep quality, which will give us more energy to do what we need to do. Work hard; sleep hard. A rested brain makes fewer mistakes. A rested body grows stronger.
Give your body what it needs and it will take care of you.