Luna and the Sun's Promise. The Puddlebrook Tales, #2

Luna Finch is the girl who notices. She noticed when a star went missing. And on a dark Tuesday morning when the sun doesn't rise and the sky stays empty as a wiped blackboard, she notices that too. The Moon arrives with a map drawn on a napkin and a worrying explanation: the Sun has been put to sleep by the Hush - a vast, woolly, impossibly cosy creature made from every snoozed alarm and every just-five-more-minutes ever wished by anyone, anywhere.
And she's grown too big, and the Sun is too tucked in, and only a child too stubborn to want a lie-in can fix it. In the Dawn Country, Luna meets Brindle the fox cub, born to be a sun-guide but not quite sure about it, and Greyling, a tiny, shy Dawn who has been helping the wrong side - because he was too scared of his own job to do it.