It is the time of the day when it is generally the quietest, where most are still soundly asleep. And it is then that many successful people have found to be their most productive time.
It is important to note that to benefit from the early morning, one has to make preparations at least the night before. That is, going to bed early, making a resolution to wake up early the next day, setting your alarm clock timings (yes, plural) and an idea of what you would be spending those precious time on.
If you fail to do the above preparations, then your early mornings would be counter productive, especially if you did not get adequate rest.