Despite the somewhat tempting impulse to stay up all night, working out your painting's compositional dissonance, recent studies suggest that that better choice might be to sleep on it. Scientific American has published "Sleep on It: How Snoozing Makes You Smarter," which argues that our minds are hard at work while we're snoaring away:

"While we sleep, our brain is anything but inactive. It is now clear that sleep can consolidate memories by enhancing and stabilizing them and by finding patterns within studied material even when we do not know that patterns might be there. It is also obvious that skimping on sleep stymies these crucial cognitive processes: some aspects of memory consolidation only happen with more than six hours of sleep. Miss a night, and the day’s memories might be compromised—an unsettling thought in our fast-paced, sleep-deprived society."

I'd be surprised if you could find a better excuse for taking a nap on a Monday afternoon. I know I could use one.