Recently, Lucy has started sleeping longer stretches at night, which is mostly awesome. She's 9 weeks old, and we're starting to get 4-5 hour stretches (or even a little longer) overnight instead of 2-3. The problem is, now I'm the one who can't fall back asleep! It's like my body thinks that because I got 4-5 hours of sleep, I'm done for the night and must not need anymore. It's almost 7am and I've been awake off and on since 3, which is going to make me miserable today. Help!