Jake Gyllenhaal's Playful Side

THE STAR IS LOVING LIFE AS AN UNCLE AND SHARES WHAT HE'S LEARNED IN A NEW CHILDREN'S BOOK

- ANDREA MANDELL

Jake Gyllenhaal is admittedly a by-the-book kind of guy. The star has leaned on research and discipline over the years to deliver intense performances in films like Brokeback Mountain and Zodiac. "In the movie industry things work on time, and there are standards and rules. So I take comfort in that, and I think I'm a pretty neat person," says Gyllenhaal, 42. But as an uncle to Ramona, 16, and Gloria, 11-the daughters of his sister, actress-director Maggie Gyllenhaal, and her husband, actor Peter Sarsgaard-he's learned to throw the rule book out.

Instead he's written his first children's book, The Secret Society of Aunts & Uncles, with coauthor Greta Caruso, a longtime friend. The whimsical adventure shows that Gyllenhaal knows that spontaneity matters far more than fastidiousness when it comes to family time. "I learned that from my nieces," he says. "If they want to stay up, we stay up. If they want ice cream before dinner, we do it. And that's fun for me."