Swami Dayananda ( Of Arsha Vidya Gurukulam ) gave the most commonsense usefulness of Getting up at Brahma Muhurtam .
He said at Brahma Muhurtam
1) Noise is less ( except for snoring family members )

2) Atmospheric Pollution due to Vehicles is less
3) No disturbance from other people like Phone Calls , people knocking at doors like Milkman , vegetable vendors , Guests , friends etc
So with the above disturbances not there ,it creates an atmosphere conducive for doing Japa , Parayana , Scriptural study provided we do not disturb others sleeping by our activity .
Having said that he said according to Medical Science a person needs 7 hrs of good sleep and hence if you get up at say 4 a..m , you must sleep by 9 a.m which means you need to have food by 7 p.m .
If you go to sleep by 11 p.m or so you will have quite less sleep ( especially if u come after a hard day's work at office ) and if u forcibly get up at 4 a.m to do meditation , you will only end up sleeping during Meditation .
So he advised people to be quite pragmatic while choosing to get up during Brahma Muhurtam . Your life style should also co-operate for such a possibility .