sleep

I am lost w/ this sleep thing.
We feed the baby and put her in bed around 9. She had been sleeping, waking up around 12 to eat, then going back to bed for about 4 hours or so. This week something changed. We'd put her in bed at 9, then she'd wake up about an hour later wanting to eat again. She kept us up till 2-3 am. When you are exhausted and ready for bed, staying up w/ a baby for no apparent reason is hard! Thankfully she wasn't cranky, just awake.. Last night we kept her awake and instead of putting her in bed at 9, we put her in bed at 10:30 or so.. We thought she'd be so tired, she'd stay asleep. That didn't work. After an hour of being asleep, she woke up again. Thankfully she went right back to sleep, so I was in bed by 1.

So I'm just lost b/c I don't know what changed and I don't get why she's waking herself up after being asleep for 1 hour. Anyone have any thoughts?!

On the plus side, last night, she slept about 6 1/2 straight hours. Our new record. So nice to sleep through the night :)