Mystery of baby sleep

I mentioned back when David turned 7 months old that he celebrated by sleeping 12 hours through the night. Twice. Actually he did it 4 times, and then he gradually went back to getting up twice a night, at his usual midnight and 5am. I was disappointed, but had learned from my experience with Katy that this might happen, so I was only cautiously optimistic to begin with.

This month has been a tough one for Bubs. He's had a never-ending cold, his two top teeth have been poking through the gums for weeks, and then, of course, he had a little incident with his finger. So I'm not surprised that he hasn't been sleeping through the night. But this is what I don't understand. Three nights ago he got up twice. Two nights ago, only once at 5am. Then last night, he slept from 7pm to 8am. Huh? I was floored. It was the first time I got 8 straight hours of sleep in probably close to a year. (Because I find it physically impossible to go to sleep before 11, so even when he has slept 8 hour stretches, it's never coincided with my own bedtime.) But what is the change? What causes him to wake up one night and not the next? I wish I knew.

And once again, I'm only cautiously optimistic. Even if he sleeps through for the next few nights, we're going on a trip and that'll fix that. But I'm encouraged that we're making forward progress. Maybe, hopefully, we're on our way to those precious consistent nights of sleep.