Why to get up early in the morning?
Our performance undoubtely depends on the performance of other people surrounding us. ALone we can do nothing. Or almost nothing. Or just a bit. Using leverage of other people our power can be multiplied. Other people can help, advice, refer etc...
So only in the early morning we can call a lot of people, ask them something. What can I do at night? Writing emails? Who will answer them immediately?
Waking up at 6 am I can spend 2-3 hours for working alone and then make a lot of calls. Of course I call simultaneously with doing some home work (cleaning and etc) with my amazing hands-free devise.