Marsha Hayles, , illus. by Hiroe Nakata. . Putnam, $15.99 (32pp) ISBN 978-0-399-23871-0

Who doesn't like wearing pajamas—especially when it's other than bedtime? Hayles (He Saves the Day ) and Nakata (Lucky Pennies and Hot Chocolate ) capitalize on this somewhat guilty pleasure with an entire calendar of no-holds-barred pajama-wearing (although some of these events are officially sanctioned, like a sick day or Pajama Day at school). The hero's bottomless wardrobe of sleepwear is matched only by his boundless gusto for life. On a "hot August night," he wears striped shorty pajamas that show his belly button—perfect for benefiting from the breeze of a fan (which he's able to reach by standing on a tower of books). At Halloween, he dons a pair decorated with candy corn and huddles with Dad in a blanket fort for spooky stories. The couplets can be clunky ("For Mother's Day May/ Making pancakes in stacks/ Or a June night away/ When I ride Grandpa's back"), and the refrain ("Time for pajamas,/ my jamas, mine-o") doesn't add much zest. But, Nakata carries the show; her watercolors capture the simple-hearted joy expressed by the narrator with a beguiling mix of delicate, downy textures and gleeful mischievousness. Ages 2-up. (Feb.)