Before Lydia was born, Cyndi and I had someone give us a copy of Babywise or Along the Infant Way. The basics of this are parent directed feeding, playing, and sleeping. It worked wonders so we did the same thing with Isaac. The same thing happened. While he is going through a phase where we wakes up at 4am or so, he sleeps very well. One thing we did for both of them was let them cry a bit if it wasn’t time for them to eat.
As Gomer Pile once said: Surprise, Surprise, SURPRISE. The Telegraph has an article talking about how it is beneficial for babies to cry a bit and not have parents respond immediately to their cries in the middle of the night.
Image from up your ego via flickr