SheFly, I usually get up at 5 or 5:30, but that is different than riding at that time. I had to remind myself that until 2 years ago, I exercised at this time all of the time... I taught a *5AM* aerobics class for 4 years and a 6 AM one for a couple of years. I truly don't know how i did this.
When I commuted from Concord to Hudson, I left at 5:45, mostly so I could be at school by 6:45 and get myself cleaned up before anyone saw me (except my boss who always drove by me when I was riding and would be awaiting my arrival like 20 minutes later!).