Darby Saxbe is a clinical psychologist, professor at USC, and one of the few researchers in the world studying how men’s brains change when they become fathers. She is also the author of Dad Brain: The New Science of Fatherhood and How It Shapes Men’s Lives, a book that explores the neuroscience, hormones, mental health, relationships, and social shifts that come with becoming a dad.
She’s also a mom of two teenagers and a returning guest on Startup Dad. We discussed:
- Understanding how fatherhood changes the brain: Why Darby believes becoming a parent is a major window of brain plasticity, similar to adolescence.
- Writing Dad Brain from both science and personal experience: How Darby’s own father, stepfather, husband, and kids shaped the story behind the book.
- Rethinking testosterone and masculinity: Why testosterone often drops in new dads and how that can support bonding, patience, and caregiving.
- Recognizing dad mental health risks: How depression and anxiety can show up differently in fathers and why dads are often invisible in postpartum care.
- Building confidence through hands-on parenting: Why dads need reps, trust, and real responsibility instead of being treated like backup caregivers.
- Making fatherhood more supported at work and at home: How better leave policies, dad communities, and cultural expectations can help men become more engaged parents.
Where to find Darby Saxbe
Where to find Adam Fishman
In this episode, we cover:
(00:00) Welcoming Darby Saxbe, Author and Professor at University of Southern California
(02:19) Celebrating the launch of Dad Brain
(05:17) How Darby’s dad shaped the book
(11:19) Writing about stepfathers, grief, and family complexity
(13:52) Why parenthood rewires the adult brain
(18:17) The U-shaped curve of dad brain changes
(22:07) Why fatherhood is both costly and rewarding
(30:04) What testosterone changes reveal about fatherhood
(38:50) Why the manosphere gets masculinity wrong
(43:56) Rethinking oxytocin, cortisol, and hormone myths
(47:14) Why dads’ postpartum depression gets missed
(51:26) Why the NICU can feel like a no man’s land
(53:48) Why the dad bod is real
(57:10) Why bedtime dads help the whole family sleep
(01:00:36) How rough and tumble play helps kids grow
(01:02:48) Why dad brain belongs at work
(01:14:43) Why paternity leave needs a better design
(01:23:48) Lightning round: sea horses, Homer Simpson, sushi, and tiny cars
Resources From This Episode:
Pre-order Darby’s Book, Dad Brain: https://bookshop.org/p/books/dad-brain-the-new-science-of-fatherhood-and-how-it-shapes-men-s-lives-darby-saxbe-phd/0dec68c3d890e5a7
Darby’s Substack, Natal Gazing: https://darbysaxbe.substack.com/
Darby’s previous episode on Startup Dad: https://www.youtube.com/watch?v=WBvgqimMv6E
What’s On Her Mind by Allison Daminger: https://www.allisondaminger.com/book
Father Nature by James Rilling: https://mitpress.mit.edu/9780262048934/father-nature/
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