I'm *so* sorry for those of you with sleepless nights! That's my idea of H-E-double-toothpicks right there!
Happily my kids take after me: they eat well and they sleep well, and always have. The first slept 6+ hours at 6 weeks, the 2nd at 8 weeks. (My pediatrician told me not to tell that to other mothers though, since it will make me despised. Sorry all!)
Truly, though, I think it's a survival mechanism for them. It's likely they wouldn't have survived this long if they didn't let Mom get her sleep!
