When I was working a full-time job, I found I could be super productive between 7am and 9am before most other people got in, then I wouldn't really get a huge amount done beyond supervisory and mentoring type work until 8pm or so when I could restart working.

Currently, on my own stuff, I work about 11pm to 3 or 4am which has been super productive but somewhat tiring. The huge benefit is almost complete peace and quiet, which really helps me focus.