There's a new book out that tells when is the best time to do just about anything. The Body Clock Guide to Better Health can help with the best time to clean house (4 pm), take a nap (1 or 2 pm), and even when is the best time to exercise (5 or 6 pm). Funny, I've just always done these things when I felt like it and if I didn't feel like it I'd wait until I did.
But don't expect this book to be a light and breezy read. It's described as "an exhaustive guide to the merits of chronotherapy, which synchronizes healthcare with the patient's internal clock." Oh my!