Personally, I prefer to do all my weight training and aerobic exercising during the hours of the night, when the sun isn't shining. I find that daylight should be preserved for daytime activities, and the night for both sleep and fitness.
Now I usually wake up around five for a moment, just long enough to do my weight exercises, and my aerobic exercising I usually do during the evening when it's just gone dark, because it's just that much more comfortable. And it's much cooler, so it's easier to go on without sweating like a pig. I hate sweating, not a good thing when trying to get fit.
What do you guys think? Is it better or worse doing fitness during the night?