Hello, Baby!

04/15/2004 at 01:00 PM EDT

Charlie's Angel
Denise Richards can attest: Her "compassionate" and "sensitive" husband can also be devilishly charming. But at 3 a.m. on a recent Wednesday morning, the lady at his side – his newborn daughter Sam – was simply not going to be soothed. "I changed her three or four times and fed her and did the burping," he says. For four hours he tried to get her to go to sleep, but she still wailed every time he left her nursery. "Finally I took her to Denise, and we put her between us," he says, "and she fell right asleep." The lesson? To heck with experts who suggest you let babies cry themselves to sleep. "You know what? No," Sheen, 38, says. "There's a time when compassion outweighs everything else."

Compassion – and gratitude. For the star of CBS's top-rated sitcom Two and a Half Men, late-night sessions with Sam have done more than perfect his diaper-changing technique; they have provided the actor with ample time to thank his lucky stars. The ones, for instance, that sparked his dimming career when he took over Michael J. Fox's part on Spin City in 2000. He began dating Richards, 33, after she did a guest stint on the series in 2001 and married her in 2002. Their first child, Sam, arrived at 10:57 p.m. on March 9. "I don't want to say he was instantly changed," says his father, West Wing star Martin Sheen, 63. "But he was instantly changed."

Two decades ago, when Sheen had his first child, Cassandra, 19, with his high school sweetheart Paula Profitt, he was but a kid himself. Riding high on acclaimed parts in such '80s landmarks as Platoon and Wall Street, the third of four actor children of Martin and Janet Sheen, 65 (siblings Emilio, 41, Ramon, 40, and sister Renee, 37, all took their father's given surname, Estevez), was a party boy less than committed, he has said, to fatherhood. Today, being a father – to Sam and Cassandra – is a top priority. "With a bigger life comes more responsibility," says Sheen, who has been sober for six years. "But it's not like I didn't earn it. It's pretty friggin' cool."

The added responsibility arrived sooner than he and Richards had planned. The two had just finished filming Scary Movie 3 last June when, on a vacation, Richards noticed she "didn't feel right. I felt tired." The night they returned to their postmodern home outside L.A., she took several pregnancy tests – all positive. A blood test by her doctor confirmed the news – and that day, during a break on a photo shoot, Sheen went outside and looked up to see a giant billboard. "It was a guy looking forlornly off into space, and it said something like, 'Unplanned pregnancy is my responsibility too,' " recalls Sheen. "People talk about God giving you signs."