Janet, This eating a lot at night is a normal phenomena in human babies that I have seen termed "cluster feeding". This is part of my anticipatory guidance for all moms, to expect this and use it as a time to relax before bed. Many babies also do it in the early morning, but mom does not mind as much. I tell moms that the baby seems to need to 'tank up' for the night, and should then sleep 4 or 5 hours. It may be related to hunter-gatherer patterns of human living where people worked in the day, ate, and then sat around the fire at night talking, singing and dancing. This is a convenient time to feed baby as well. Daytime feedings in these societies seem to be short and frequent, without interrupting moms work. At night there is time to relax and enjoy. As for formula making babies sleep, the amino acid composition is soporific, and formula is not efficiently utilized by the body as fuel (baby is actually getting less energy out of it ) which according to some researchers (Zeskind especially) is not good for human babies, predisposing them to SIDS. My theory on things that worry people: reframe it so it is expected and some purpose is seen in it and it will be far less threatening. Hope this helps. Catherine Watson Genna, IBCLC