It depends how old your baby is. Babies know what they need, unfortunately, and that means missing a good chunk of sleep for a while sometimes. If you have an infant who wants fed at that time, feed her and then put her down to sleep. If she tries to stay up longer, and just wants to play, try putting her to sleep anyways, with a full belly. If that doesn't work or if she is a little older, just give your doc a call and ask the nurse for advice, they usually have tips on this sort of thing, and know your situation.