My DD is 5 weeks old. She has fallen into a nighttime sleeping pattern where she'll sleep for a long stretch in the first part of the night (anywhere from 4 to 6 hours), but then in the second part of the night she won't sleep longer than 3 hours. In fact it's usually around 2.5 hours. When she wakes up after her long stretch, I change her and feed her until she's full, burp her and then put her back in the crib. When I put her back in sometimes she's asleep and sometimes she's awake but drowsy. She's able to settle herself back to sleep pretty quickly. This is pretty much the same thing I do before I put her down in the evening for her long sleeping stretch so I can't figure out why the difference in sleep length.

I'm trying to figure out why she has this pattern and what I can do to extend the second half of the night like the first. Any thoughts or ideas?