Why do you want to cut milk at midnight? your bb is only 6 weeks wor.
Mine is 6 week too, I didn't cut the milk at midnight. But my bb will drink less say 2oz if drink at midnight (usually she will drink 4oz), you bb is so "ging" , she/he can drink 6oz.
My Chinese doctor says that you can try to feed him/her water when he/she wakes up at midnight. Then let him/her sleep till morning. See whether it works.
Did your son/daughter get 6-in-1 injection? My daughter did it two days ago. It seems that she is very sleepy these days and losses appetite (eat very less milk). Does your son/daughter have same reaction?