I've had some extra duties in the last few days, meaning I'm not getting to bed at my normal time. And what does that make a person? Crabby.
I could be crabby and have felt a little crabby. But I'm so conscious of it that I'm able to modify it by willpower. So I'm not lashing out mercilessly. I'm keeping a level head.
There's something about the power of sleep. I guess we might say your head is like a library. But if kids come in and visit the library, and there isn't any adult supervision, they would scatter books all over the place.
Sleep is like the patient librarian, patiently putting the books among the stacks. Or let's say there's an evil librarian, surreptitiously piling the books on a cart and hauling them out to the trash, then making a note that the kids from Mark Twain Elementary stole them.