my 4 month old go to sleep until 3 am then she will sleep 8 hours is this normal.She has a couple of naps during the day never more than an hour. She is a snacker and usually only feeds for about 10 mins at a time feeding every 3 hours or so. She is gaining weight well and happy and healthy.She is breast fed. I was hoping that she would sleep from midnight by now as its very tiring