What's Best for Creativity?

This morning, I woke up extra-early for work, like I do everyday, so I could spend at least a few precious minutes staring at my computer, working on the next novel (I obviously find plenty of time to do not-work at my job, but the kind of focus that I need to work on a novel vs. an essay or a blog is just...different).

Feel free, at this point, to pat me on the back for being saintlike in my devotion to my craft. That half-hour of zombie-staring at a screen, then frantically typing a few sentences I'll fiddle with, slowly, the next morning is pretty much heroic.

But since today is Friday, and my body clock just doesn't want to be in bed before 12 or 12:30 most nights, I was extra tired.

Stupid tired.

So of course I thought it would be a good idea to introduce a second maybe-love-interest to a story in which I intend there to be zero actual romances.

Terrible idea? Or best idea ever?

That depends on me, of course, and whether my skepticism towards teen romance (which I maintained EVEN AS A TEEN) will win this fight; but it did get me thinking (slowly, thickly, rusty-gears style): when do you get your best ideas?

There are a lot of tired maxims about creativity: "you'll get great ideas in the shower," or "the best ideas come when you least expect them," or "write drunk, edit sober."

Is there any truth to any of them? Is my brain's being so painfully tired that I think, right now, I can actually feel it throbbing, a good reason to trash everything I wrote this morning...or to trust it? Should I start pulling out my computer around the start of cocktail number two?

What's the best state to be in to GET ideas (obviously this is all personal)...and what's the best state to be in to execute them?