Nodding off

With few exceptions, especially since school started, bedtime is 9 p.m. Big sister can argue all she wants, once the little hand hits the nine and the big hand is straight up, it's time to go down.
But she has recently wanted to be rocked right before bedtime because she knows we rock little sister to sleep.
So, we ask her about 15 minutes ahead of time if she wants to go rock. She always says yes. During that time I tell her stories and we talk about her day at school and other things.
Having had a few hard days at work last week, I nodded off a few times during our rock time, which upset big sister greatly. I mean, after all, that is her time.
The beautiful wife asked Big sister if it was time to rock. She said yes, but only if you do it mommy.
Rocking big sister to sleep isn't exactly the beautiful wife's cup of tea -- "you make my legs go to sleep," she said.
"Yes," big sister said, "but daddy's head goes to sleep."