As a teenager I used to go to bed late in the night and then slept till noon. Then for the year I was in the army I had to give up on this habit. By the way I’m mostly pacifist but here in Bulgaria we had a compulsory military service at that time. Later after my discharge from the army I returned to my previous sleeping habits again. I was fiddling with my new toys – learning Linux, computer networks. I was hanging a lot on the IRC (actually I was the administrator of an IRC server). I even had some problems in the office because I was often late for work. I’m not sure why was that – probably because it used to give me some false sense of having more time?
Don’t know how happened but now I prefer to wake up early and in general to synchronize my active time with the bright daylight time. I definitely get better sleep at night when it’s dark and quiet. And then I feel fresher and more focused when it’s bright and sunny outside. It’s not bright and sunny during the winter but it’s still better. Moreover when I wake up early enough I don’t have to rush for work and my entire day is much less stressful. I do my breakfast, quickly scan the news headlines, go through the bathroom and dress up at a what I’d consider fairly relaxed speed. By the way most of the year I commute to work on a bicycle. This is not only far less stressful than driving but also saves me some time cause I have to go less often to the gym. Actually my situation is a little bit more complicated cause I work in shifts. I’m also on-call some of the nights. And I do my workouts in home without going to the gym… but you get the idea
I think that one of the main reasons the early rising has so positive effect on me is that it gives me enough time to tune up to the coming day and to calibrate my internal clock as well. You know how time flies when we’re busy, but really drags when we’re waiting? By having some free and calm time in the morning, as opposed to rushing through the door ’cause you are late for work, makes a difference to your perception of time for the whole day.
I really find it useful to step back and just look through the window for few minutes every now and then, just to slow down my time perception. It has the added benefit of relaxing my eyes and gives me some rest in general. And if you think that’s too wasteful – think about the time lost in inefficient or ineffective work, useless conversations, procrastination…
In order not to return to my sleep-till-late habit I use alarm even on the days I don’t need to wake up early. On these days I put it a little bit later to allow for 08:30-09:00 hours of sleep. It serves two purposes: on one hand I don’t oversleep and on the other hand if I wake up earlier I don’t have to get out of the bed because it looks like it’s late. I could just lounge till the alarm goes off.
P.S.: There’s a very interesting wikipedia article on the role of melatonin in humans.