I would like to draw your attention to. "The story I like best about why there's a dawn phenomenon (although it's clearly apocryphal) is that we were designed that way so farmers would have enough energy on-board to go out and do their early morning chores without stopping to eat breakfast first".

You may call it apocryphal but I strongly believe that it is the closest we can come to finding the cause of dawn phenomenon. Human beings have evolved from hunter-gathers to nomads to settled communities. As we evolved, we made some adaptations to suit the lifestyle. Dawn phenomenon was a survival measure very crucial than and even more crucial now. "The early bird get the worm". Most successful people start their day very early and get all their work done in the first few hours of the day. This is the time the body is at its peak performance levels. This can be proven by the fact that the body's metabolic rate is highest in the earlier part of the day.  The human body is designed to work in the early morning (stay out of the midday sun and prevent cancer) so dawn phenomenon should be a good thing for all of us. Just kick it to your advantage by making a few lifestyle and dietary change.