Little Jack

Don't I look rested in this picture? Jack slept through the night last night, with a little help from me. He woke up about every hour, but I got to him each time before he got fully awake and was able to settle him back to sleep. Part of our "go to sleep" routine is me rocking him a little and humming "Amazing Grace" just before I put him down, and I'm beginning to wonder... will he get sleepy for the rest of his life whenever anyone sings Amazing Grace?