Zach has actually started singing himself to sleep with Twinkle Twinkle. I haven't been able to get it on video yet, this is the best one I have so far. He usually really sings it out. I love his little hand motions though, especially the diamond that he focuses so hard on creating with his fingers.
Just double click the video to see the whole screen- I'll figure out You Tube one of these days. Just not today.