"A large number of novelists and poets, for instance, wake up early in the morning and try to get some words on the page before other obligations kick in. Composers, I've found, almost invariably take a long daily walk. And if you suspect that caffeine is the real engine of a good deal of creative activity, well, you may be on to something."

Early morning does seem to be a common theme:

One of my favorite habits from the Daily Rituals research came from Nicholson Baker, who also prefers to work just after waking. “The mind is newly cleansed but it’s also befuddled and you’re still just plain sleepy,” he told me in an interview. “I found that I wrote differently then.” Baker likes this feeling so much that he developed a strategy to squeeze two mornings out of one day. He will get up around 4 or 4:30 a.m. and write for an hour and a half—but then he goes back to sleep until 8:30 and gets up again, this time turning his attention to “daylight kind of work,” like transcribing an interview or editing what he wrote during the first morning session.

My dog wakes me up super early to go out for a walk.  I find that time enormously productive in terms of coming up with ideas.  Then I write them down (in PBworks, of course) and go back to sleep.

A good reason to get a dog, btw.