I don't know - I just know that all day, Julianna has only slept while she's in my arms nursing. Normally she takes one serious nap for a couple of hours, sometimes two - and today, she's only napped sporadically. She dozes off nursing, and then jolts awake when I lay her down. It's five forty seven now, and my arms ache from holding her all day, and I'm exhausted because she was up most of the night. I've had four cups of coffee, trying to stay awake, and could go to bed right now and sleep all night. In fact, I think I'm going to go try and catch a little sleep before Marc gets here. Thank goodness for co-sleeping, because I know it would be a million times worse if I had to keep getting her up out of the crib to feed her, but she was really restless all night, so I didn't sleep all that well to begin with, and then a full day of no napping - I'm totally wiped out.
Oops - she just woke up. Again. No nap for Mama.