9 am is when the morning becomes the day.

...This is what Jack said to me this morning when he let me sleep from the everyday hour of 6am, to the very luxuious hour of 9 am. "You slept in so so late, mama." "Hm. Thanks for letting me. It's only 9 o'clock, though! That's a very normal time to wake up, I think." "No. It's practically the middle of the day!" "Actually, it's as far from the middle of the day as it is from our regular wake up time. Count it and see." "Oh. Yeah. Well then, 9 am is when the morning becomes the day. Let's get going."