Waking up at 5am to code
A lot of commenters have talked about the pros of this routine, and there are many.  Few interruptions, working while your mind is fresh, working within a regimen, etc.However, if you don't have an equivalent amount of discipline on at night to get enough rest, you will quickly burn yourself out.  I did this routine for a lot of the second half of 2011, and since I'm a night owl by nature (going to bed at 12 midnight is 'earlyish' for me), the lack of sleep quickly caught up with me.  My project was actually getting some traction though, so I basically spent about four months in a sleep-deprived haze and consuming about 400 mg of caffeine a day just to function.So I guess what I'm trying to say is, if you're like me and you go to bed at 1AM, wake up at 9AM, and go into work at 10AM (a very common engineer schedule), then it's not just a case of setting of your alarm clock but really adjusting your lifestyle so you're not fundamentally sleep-depriving yourself.