[CharlesW]

Another consideration is that people write differently depending on their state of mind/body.

I effectively can't do "work" writing at night. But I've found that fiction, humor, and other creative writing can benefit from being in a different headspace. Being tired to the point of feeling a bit punch-drunk can take you to interesting places. The few times I've truly surprised myself, I was writing in a somewhat (not drug-induced) altered state.