In my head, I associate the words "Respect Your Energy" with something Merlin Mann said or wrote, but I can't immediately find it online.
I wrote in "No TV, No Console" that "evenings are sometimes for entertainment, but sometimes they're for work too". Let me extend that to all twenty-four hours of the day: work when it suits you to work.
Think about it: as indie software developers, we depend on so little infrastructure or service that we can carry on our trade from literally any corner of the planet with an IP address and a mains socket for our laptops.
I try not to go down that line of thinking too far, because I always end up wondering why I don't live in, say, Italy. Anyway....
One of the worst problems of living in our current urban conurbations is that everyone tries to do the same things at the same time. Go to work for 9, come home at 6, go to the park on Saturdays. You, as an indie developer, can and should do things when it suits you.
Personally, I love working in the mornings. I don't like dealing with people in the mornings, but if I can get to my desk for 7am, I can make a good dent in the electronic world by 1pm. By contrast, I am a useless blob of mental jelly between 1pm and 5pm. I never expect much of myself in the afternoons, and that's by design.
So, my message here: reflect on the times that work for you, and work then.
A note of caution, though. You have to work. To make it in any business you have to work and work and work and work. Don't let this piece of advice serve as an excuse to let time drift away. As Brent Simmons memorably wrote in Advice for Indies:
"But you have to actually build it. You have to work every day. You have to sit in the chair and stay seated. And sleep and come back to the chair. You need to wear out that chair and then buy a new one and then wear out that one."
You have to actually build it.