When I talk to my friends who have a "regular job" (meaning they sit at an office from 9 to 5 M-F) they are often mesmerized at my hours. I like to say that my office is wherever my brain and laptop are and I work when there's work to be done. This tends to send the misconception that I go out and sit at coffee shops for most of the day not really doing anything. However, they don't see this side - the fact that I'm up at 3:24 in the morning because I had an idea for a client that I needed to get down right away.
Why? Because right now the juice is in me.
Being a writer is somewhat of a two-sided coin. I write every day just to keep myself disciplined. I also consider myself "on call" with the muse. If an idea pops into my head, I'll work with it right away (no matter what time it is) because I know that I'll never be able to replicate the vigor of my original thought.
So today my office hours are at 3:30 in the morning. But hey, it still beats the heck out of a desk job!