S.W.
I always encourage people to feed a high protien snack like peanut butter and jelly right before bed when I hear this problem. Both of my boys (now 4 and 7) went through periods when they stopped sleeping through the night, long after they have been sleeping through the night and we finally figured out they were starving! My idea is that during high growth periods, they just can't make it long without food. The snack before bed (around 8pm) would keep them until 4 or do and then I would feed them some more and put them back to bed until 6 or 7. Good luck.