Lisa Graff is the author of middle grade novels as well as picture books, including It Is Not Time for Sleeping, illustrated by Lauren Castillo. As a child, Lisa often wondered about the secret adventures of the little men in the walk signals. She lives with her family in Pennsylvania. lisagraff.com, Twitter: @lisagraff Christophe Jacques is an illustrator living and working in Flanders, Belgium, where the walking signal is a little green man instead of white. Instagram: @atelier_la_fermette