Was your baby up a lot at night when they learned to sit on their own? DD doesn't sit herself up, but stays unassisted now. She has been awake a million times a night since learning, but I didn't put 2 and 2 together. Last night she actually slept.....maybe that is what was causing it?
I didn't think of that one as a sleep interrupting milestone, since she doesn't do it herself, you know? Hopefully I am wrong!
Re: Learning to sit
I know this probably doesn't help you, but it was completely the opposite for us. He learned how to sit, started getting two teeth, and learned how to push up on all fours all in the same week that he started STTN.
I think all the activity just wore the poor guy out! Sorry I'm no help!
The Mouse ~ 06.12.08 | The Froggy ~ 02.23.11