I used to be most productive around 02:00 - 04:00, but recently (like a year or something) it seems that my most productive times seem to have moved to 05:00 - 07:00 (when I am awake at that times, which is not really often) and to evenings. I think this was caused by trying to tend to somehow more normal and regular schedule in 2010 and then complete burnout (I stayed awake till 09:00 while doing nothing much meaningful and then slept to like 18:00 every day) in March of 2011.
