Episode 434: How Women’s Brains Change On Their Periods

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Sep 23, 2025

Dr. Sarah Hill, a seasoned researcher and author of *The Period Brain*, sheds light on the intricate effects of menstrual-cycle hormones. She discusses the evolutionary reasons behind PMS and how hormonal fluctuations can affect women’s mood, energy, and sexual motivation. Learn why progesterone doesn't always enhance well-being during the latter cycle phases and how estrogen influences desire. With insights on navigating intimacy in sync with the menstrual cycle, this conversation offers valuable knowledge for understanding women's health.

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INSIGHT

Rethinking Progesterone's Purpose

Progesterone's role in the luteal phase puzzled researchers because its effects didn't obviously support pregnancy goals.
Sarah Hill dove into progesterone science to explain PMS and luteal changes.

INSIGHT

Cycle As A Monthly Gearshift

The menstrual cycle shifts the body between attraction (estrogen) and pregnancy (progesterone) modes every ~28 days.
These hormonal shifts cause systemic changes including metabolism, immune function, and sleep.

INSIGHT

Why Progesterone Can Cause Anxiety

Progesterone metabolizes into allopregnanolone, which boosts GABA and calms the brain early in the luteal phase.
Rapid progesterone drops can trigger anxiety in women who lack cellular resilience to hormonal change.

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It is well-known that PMS symptoms can deeply affect how women are feeling, including their mood, pain, and energy levels. But why exactly does this happen? Today, we’re going to dive into the science of sex hormones and the menstrual cycle, including how hormone levels affect women’s sexual motivation and tips for navigating sex at different phases of the cycle.

I am joined by Dr. Sarah Hill, the author of This is Your Brain on Birth Control. She has spent most of her 20+ year career studying women, relationships, and health. Her latest book is titled The Period Brain: The New Science of Why We PMS and How To Fix It.

Some of the specific topics we explore include:

What’s the deal with PMS? Why did women evolve to feel like crap for half of the menstrual cycle?
How do the rise and fall of different hormones during the cycle affect women’s brains?
Progesterone is a hormone that’s supposed to make us feel good. So why doesn’t it have that effect during the second half of the menstrual cycle?
How do estrogen and progesterone affect sexual motivation and desire?

You can check our Sarah’s website to learn more about her work.

Got a sex question? Send me a podcast voicemail to have it answered on a future episode at speakpipe.com/sexandpsychology.

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Credits: Precision Podcasting (Podcast editing) and Shutterstock/Florian (Music). Image created with Canva; photos used with permission of guest.