Celebrity Parents Justin Hartley Gives Pregnant 'This Is Us' Costar Mandy Moore Parenthood Advice: 'Get Your Sleep Now' Justin Hartley is dad to daughter Isabella, 16, and Mandy Moore is currently expecting her first child, a son By Benjamin VanHoose Benjamin VanHoose Twitter Benjamin VanHoose is an Associate Editor on the Movies team at PEOPLE. He's worked at PEOPLE for over three years as a writer and reporter across our Entertainment, Lifestyle and News teams, covering everything from the Johnny Depp v. Amber Heard trial to the Oscars. He regularly covers red carpet events and has interviewed stars like Drew Barrymore, Ryan Reynolds and Kirsten Dunst. He previously worked as a copy editor at Topix Media Lab. People Editorial Guidelines Published on February 2, 2021 12:19 PM Share Tweet Pin Email Justin Hartley has some sage advice for mom-to-be Mandy Moore. Appearing on The Kelly Clarkson Show on Tuesday, the 44-year-old This Is Us actor offered his tips for costar Moore, who is currently expecting her first child with husband Taylor Goldsmith. Hartley — who shares daughter Isabella, 16, with first wife Lindsay Korman — explains whether he's given Moore, 36, any advice yet on set. "You know, I haven't yet, but it's unbelievable, this woman is radiant," says Hartley. "You would never know she's pregnant. She looks like she could run a marathon. But I would tell her, if I did have to tell her something, I'd say, 'Get your sleep now. Because when the babies come, you're not gonna sleep much.' And if you do sleep, it won't be the same quality of sleep." Mom of two Clarkson, 38, agreed with an "Amen!" "Oh my — I literally, on Christmas vacation, my son [Remington Alexander], I woke up in the middle of the night and he's 4, and I woke up and I couldn't breathe," the host recalls. "I was like, 'What's happening?!' And he was having a sleepover ... and he was asleep on my body. ... I was like, 'Bro, get off of me!' It is the worst sleep!" Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories. Michael Bezjian/Getty RELATED GALLERY: See Pregnant Mandy Moore's Sweetest Baby Bump Photos Moore, who plays Hartley's mother on the drama series, recently opened up to Romper about her road to motherhood, sharing that her husband, 35, has a natural knack for parenting. "I think he's been suited to be a father for pretty much his whole life. He's been gearing up for this," she said. "Like in the morning, it's funny, I'll reach for my phone and he'll reach right for whatever baby book he's reading." Mandy Moore. Mandy Moore/Instagram Adding of Goldsmith, who would normally be out on the road if not for the pandemic, Moore said, "We wouldn't have spent this gestation period together — he would have been touring. And it would have been fine, but having this experience together makes me feel even more solid and even more excited to be a parent with him." Moore added that she wants to "raise an intelligent, feminist, loving, compassionate young man, who respects women, and who understands boundaries."