The Period Brain: The New Science of Why We PMS and How to Fix It—A Manifesto for Women

by Sarah E. Hill

Do you feel like you’re riding a premenstrual roller coaster every month that leaves you feeling hungry, tired, angry, sad, and unsexy?

Leading researcher and women’s hormone expert Dr. Sarah E. Hill explains why we feel so universally icky before our periods— and what to do about it. The problem isn’t that women are hormonal; the problem is that the second half of the menstrual cycle—the luteal phase, when the hormone progesterone rises and estrogen decreases—has been systematically ignored by science and medicine.

Progesterone is at the heart of every feeling we associate with PMS: it affects our daily sleep and calorie needs (hello, cravings!); whom we’re attracted to; our sex drive; and—as every woman can attest—our mood. Because the luteal phase is understudied, every bit of health, diet, and relationship advice you’ve followed is based on that first, estrogen-glow half of the month or, worse, was designed for men.

The rules that work for us in the first two weeks of the cycle don’t always fit in the second, causing most of us to spend half the month following advice that is completely at odds with the way our bodies work at this time. It’s no wonder we feel awful! Dr. Hill demystifies how our bodies work, so you can work with your hormones to:

· Sidestep PMS “cravings” by eating more –you burn up to 11% extra calories in the luteal phase!

· Exercise in a way that’s invigorating instead of draining.

· Understand your sex drive, and why sex has different meaning across the month.

· Quit bad habits more easily thanks to progesterone’s addiction-busting properties.

· Navigate motivational and energy dips without added stress.

· Incorporate anti-inflammatory foods and habits to naturally ease PMS.

The Period Brain is a science-tested roadmap to understanding PMS and PMDD. It’s time we demand a better month, every month – and usher in a new era in women’s health. Period.

Genres: Nonfiction, Science, Self Help, Health, Medicine

304 pages, Hardcover

Published September 30, 2025

About the author

Sarah E. Hill, PhD, is an associate professor of psychology and a leading researcher in the dynamic and rapidly expanding field of evolutionary psychology.

Reviews

[Kelli · Rating 4 out of 5]

Thanks to NetGalley and the publisher for an advanced copy in exchange for an honest review.

Hmm I feel very similarly about this book as I do about Come as You Are: The Surprising New Science that Will Transform Your Sex Life- love the message, learned a lot, but I just really don't like the writing style.

This is a short little book that explains female sex hormones (estrogen and progesterone), how they cycle each month, and the effects they have on your body and mind (aka PMS), in addition to tips on mitigating these effects. Her goal as a hormone researcher is to educate people with these hormones (she is careful to point out in the beginning that all bodies are not the same, and this does not apply in a strict gender binary at all) on how their body functions, because as she rightfully points out, most of us are never taught any of this stuff.

It was super interesting to learn about how my hormones work, testosterone included, and I really liked her perspective on PMS- that it only feels so bad because we do not understand what is going on and try to live our life as if we don't have hormonal cycles and feel crazy, rather than working with our bodies and adjusting our diets, exercise routines, and sleep to fit the needs of where we are in these cycles each month (of course, with the exception of some who have things like PCOS or PMDD requiring further care).

I am curious to try out some of her tips (you DO need more calories and sleep in the luteal phase!) and start to track my cycle a bit more going forward.

My only quip was that the writing style is not my favorite, as it comes across like a teenager trying to explain something (lots of cursing, pop culture references, simple phrasing, etc.) which is just not my preference when reading a book about science, though it might appeal to you! I also thought all the content of this book could be written in like a single long note, because there was a lot of repetition and too much " and that's what you'll find out soon" sort of thing, rather than just getting to the point.

[Abigail Franklin · Rating 4 out of 5]

The science was interested and the practical advice was just “eat plants and move your body”

[Kate Soupiset · Rating 3 out of 5]

This is the longest review ever but I’ve been stewing in my thoughts on this book for almost two months! TLDR: I won’t be turning my whole life routine around because of a single book and at times this felt like a chore to read, but I do think it contains some valuable information.

My biggest takeaways are the ways estrogen and almost more importantly progesterone influence menstrual cycles. I also had not heard of “cellular plasticity” being a factor that contributes to PMS. PMS has been such a constant in my life I’ve never thought it could be any other way so this book had a lot to offer in terms of things I can try to change that.

That said, I also read this book at arm’s length. As a Maintenance Phase devotee, I am skeptical of many science-y self-help books. This one does seem genuinely researched and I acknowledge that the author is writing about a topic *because* the research is limited. But it also makes me wary to take health recommendations based on that kind of research.

I would love one of the many people in my life who is getting a degree in medicine or immunology to read this and tell me if anything raises red flags lol.

I did start tracking certain symptoms for the first time in concurrence with reading this and it’s been very eye-opening. I think Hill does do a decent job of reminding the reader that what works for one person does not work for everyone and that’s why “body literacy” is so important. Even with all that acknowledgement however, I still was frustrated with some of the recommendations because they assumed certain things about the reader (although I get that the author needs to sell her book to lots of people!!). Hill said in the early pages that gender and sex are not binaries and then went but I will be saying “women” when referring to people who menstruate for the rest of the book for clarity. I don’t know if this is a frustration I have with her or the fact of science communication possibly requiring that kind of simplification.

Oh ALSO this book was horribly repetitive at times. Not just in a necessary way of being like “remember that concept I discussed 50 pages ago?” but like within the same page or even the same paragraph. Authors gotta hit that page count!!

[Carolyn · Rating 3 out of 5]

I thought the science of hormones and their function in the body was beautifully explained. This topic was new to me and it was a nice introduction to understanding my cycle, the importance of listening to my body, and sexism in science and society at large. However, the book felt extremely repetitive at times, and sometimes the author would insert her own opinions in a way that felt too anecdotal for a science book. I would recommend that everyone learn about the female hormonal cycle, though!

[Emma · Rating 4 out of 5]

Having a uterus is awesome

[Manda Ridds · Rating 2 out of 5]

I don’t normally write reviews, but I felt the need to do so for this book. I’ll keep it short and sweet(ish).

I picked up this book to learn more about the science behind our menstrual cycles and some of the issues that typically plague us in the luteal phase. I have issues with PMS, so this book was of interest to me.

While I found some of the science helpful in this book, the book felt more like an overly opinionated ode to women that men are the bad guys and women are always left in the dust. I do agree that women need to be studied separately from men since we do have two different bodies, but I did not pick this book up to read about how men suck and women deserve more. It took away from the purpose of the book and had me frustrated every time I began a new chapter where I had to read more about how men have been studied more than women. I get it. The author is upset about the disparities between men and women. But why did she choose to insert her opinions about that in this book? I thought I was reading a book about science, not to be preached to about how women deserve more.

[Madison Geery · Rating 4 out of 5]

Every woman should read this book. This book peeled back the curtains to share impactful our cycles were on every single aspect of our body (and how medications impact us differently at different points in our cycle)! I loved the recap sections at the end of each chapter with helpful guidelines of how to optimize your health in realistic ways. Thank you to netgalley and the publisher for an advanced copy of the review for my honest feedback!

[Margaret Balwierz · Rating 2 out of 5]

This book seems more like a conversation with a friend or a health influencer, rather than medical research. While Sarah E. Hill is a Evolutionary Psychologist, not a gynecologist or endocrinologist, she does seem to present the topic of menstrual health in a way that lay people can understand, especially since it not a widely discussed topic. I think this is a good book for a jumping off point to learn more about the menstrual cycle and how you need to adjust your life to work with your cycle, not against it. It brings up some worthwhile points of treating the whole body and system, rather than just the menstrual symptoms, BUT it is very generalized advice, and should definitely be talked about with your own health care providers. She seems to have a bias toward "natural" methods, which there is nothing wrong with, but again, should be talked about with a healthcare provider who knows your specific needs especially when introducing or coming off of any sort of supplements or medications.
I'm not a fan of her writing style, and while she tries to address medical misogyny and sexism, and the overall fear of topics relating to menstrual health, it comes across as more "boys suck" rather than a critique or a call to fix the broken system to provide better understanding and research support for these topics.
Thanks to NetGally and William Morrow for this ARC.

[Meg Hennessey · Rating 1 out of 5]

Atrocious science and atrocious writing. I only managed to read a few chapters and skim a few more, as the innumerable scientific errors and poor communication style were too much to bear.

For starters: multiple graphs and illustrations are comically childish. They lack correct labels on the axis, error bars, p-values or any indication if the results are statistically significant. I imagine this is because the author wants this book to have a more "approachable" style, but the title is called "the New Science of Why We PMS" and the author leans a great deal on her scientific credentials. So it is also quite disappointing when you see her repeatedly leap to conclusions that should instead be the basis for research. One example is at the start of Chapter 7 where she plainly states on one topic: "This [has] only been studied in heterosexual men, but I am guessing that lesbian women find their partners sexier at high fertility too." Guessing?!? That is precisely the kind of question that would make for an interesting hypothesis, but certainly any researcher worth their salt would not presume to know what the answer would be. There are many other examples like this throughout the book, too many to list here.

Similarly in Chapter 7 she cites a statistic that 50-70% of women do not consistently achieve orgasm through intercourse alone as evidence that, in her words, "not all women's bodies are equipped to [orgasm]." This is an appallingly shallow conclusion, in part because there is a considerable body of research on this topic that shows many different factors influence whether a women can orgasm and how frequently (such as partner type, sexual education, cultural upbringing, prior experience, the list goes on and on). I am baffled why the author would draw the conclusion that this statistic indicates women just aren't meant to orgasm or why she would not reference other research in this field.

Speaking of references, you'll note that there are essentially no references cited throughout the book, only a compendium of papers listed at the end. So if you'd like to find which paper some statistic comes from, you have to just do your best to suss out which citation is most likely. This isn't the gravest error, but certainly does not lend credibility to the author.

Overall, this book reads as the manuscript of a researcher who lets her per-conceived notions guide what conclusions she draws from data, rather than the other way around. It doesn't appear the book went through any significant fact checking or review (there are multiple grammatical errors that presumably an editor would've caught). It seems much more in the vein of the numerous pop-science articles that are churned out just for a publication to have some content to show, rather than substance or validity.

While her purported mission - to help women understand their bodies- is admirable, this kind of "science" writing only helps to murky the waters. I'm not sure how this author runs a research lab of their own.

[Morgan Fisher · Rating 4 out of 5]

Sometime in 2019, Sarah Hill’s This Is Your Brain on Birth Control popped up on an audible new release newsletter. The title was catchy and I, a long time user of the pill, was intrigued. I listened to the audiobook and repeatedly rewinded to replay everything, needing to hear the words two or three times. I was astonished at the suggestions, and although they were only just correlations, it sent me down a path to actually learn my body, something that I, at the time a 27 year old woman, had never done on this level. This was a catalyst for me to deep dive into other books about the fertility, hormones and women’s health and so I was stoked to see The Period Brain and eager to dive in, knowing Hill's research as a part of my hormone appreciation origin story.

Did I learn anything new? Yes, and no. I gained a deeper understanding of the superficial facts I have known for the last five years since going down this hormone rabbit hole and becoming a user of the Fertility Awareness Method. But, do I read only to learn new ideas? No, I read to learn and there’s helpfulness in repetition. If you were to only read one book about hormones though, I wouldn’t start with this one: I’d go for one of first four I list below.

What I liked :
+ The Science! I loved understanding what progesterone truly does in the body AND the brain, and the biological reasons, in addition to the research behind the science and how we’ve gotten the information we have so far
+ Learning about other products and resources in the market to expand my knowledge. I am now going to dive into the impacts of glucose and understanding inflammation
+ Chapters 6-10! I would re-read these in a heartbeat

What I Didn’t Like :
— Censorship of curse words: write them fully or don’t curse at all; ‘sh*t’ and ‘f*ck’ feel like they cheapen the text
— More charts and infographics would have been immensely helpful

Similar Books I Recommend :
This is Your Brain on Birth Control (Sarah E Hill)
The Period Repair Manual (Lara Briden)
Taking Charge of Your Fertility (Toni Weschler)
The Fifth Vital Sign (Lisa Henrickson-Jack)
Eve (Cat Bohannon)
All In Her Head (Elizabeth Comen)

Thank you to NetGalley and William Morrow Books for the ARC and the opportunity to read and review this title.

[♡ Lisa - Can't talk, reading... ♡ · Rating 5 out of 5]

The Period Brain blends popular science and the latest research with health and lifestyle advice in an interesting exploration of how the luteal phase works and why a better understanding of this phase of the menstrual cycle is important to naturally cycling women's overall health.

Sarah E. Hill is clearly passionate about women’s health and demonstrates how a system based on the male body as the default fails to account for the female body’s intricate dual hormonal system and cyclic nature (“bikini medicine”), which has led to the exclusion of women from the medical system and a great deal of ignorance, stigmatisation and medicalisation around our normal hormonal fluctuations.

The author argues that when we stop applying what works for the male body's testosterone-based ‘steady state’ to the female body, we can start feeling and functioning better throughout the month. She provides insight into the luteal phase and how we can sync diet and lifestyle around the effects of progesterone on the brain and entire body for a smoother transition from ovulation to menstruation. I couldn’t agree more that one-size-fits-all recommendations have been given to women for too long, meaning that we are so often working against our hormones instead of with them. This mismatch, argues Hill, is a contributing factor to PMS.

The book ends with a moving and convincing rallying cry for equality in research, medicine and pharmacology for a future where women are no longer seen as small men and where we reimagine our relationships with our bodies, focussing on wisdom, not pathology, so that we can celebrate our cycles as normal and wonderful.

[Abby · Rating 4 out of 5]

A good deal of what you’ll find in the “hormone health” world is pure conjecture, leaving women to cobble together a trial-and-error and word-of-mouth approach to hormonal sanity. Sarah Hill does a wonderful job explaining why this is: studying women has historically been “too hard” for Big Science. The standard for including women in clinical studies is to ensure they are on days 3-7 of their cycles: a time when hormones are lowest (and they are most similar to men hormonally). This would be fine if variations in cycle phase didn’t matter much, clinically. But as Hill shows, 1) this is an assumption much scientific research makes without any evidence and 2) what evidence does exist suggests a significant difference.

The second half of the book looks at the limited research on ways to improve hormonal health and well-being, including Hill’s own studies. With a critical and reasonable eye, she demonstrates how the available science vindicates intuitive concepts like nutrition and exercise cycle syncing, while being honest about what practices have yet to be rigorously studied.

[Ula Tardigrade · Rating 4 out of 5]

After centuries of neglect, the female body is finally becoming visible in Western science. There is an increasing amount of discussion about the differences between our bodies, as well as how research has traditionally focused on men. This has led to many misconceptions and blatant biases. This is most evident in the formerly taboo topic of menopause. Not only are there many new articles and books examining this phenomenon, but it has also become part of popular culture. Just look at TV shows, from Fleabag to the recently released Riot Girls.

It's about time we start talking about periods and PMS in a levelheaded manner, too. This is exactly what this book is about. Blending popular science and self-help genres, it provides all the facts, personal stories, and practical tips. It's certainly worth reading!

Thanks to the publisher, William Morrow / Harvestand, and NetGalley for an advanced copy of this book.

[Sophia H · Rating 3 out of 5]

I’ve decided to give writing a book review a try, so here it goes. This book was 3 stars, averagely good as I feel i’ve walked away from reading this with more knowledge than I had prior to starting it. I’m not one to typically this genre of book: non fiction, self-help etc. but I was satisfied with what I learned from this as the information proved how little research is done on women’s health and wellness and how much more research and studies need to be done. A woman’s luteal phase and menstrual cycle in general is individualized and complex and we have to go digging for information on our own as there is no “one size fits all” method to deal with the hormones, moods and symptoms that occur within this phase. Even though at some parts the information felt redundant, it has made me intrigued to learn more as this affects a woman every month. Overall, this book provided a solid foundation to the complexities of the women’s luteal phase.

[Sammy Stitt · Rating 5 out of 5]

Cannot recommend this book enough; it is a masterpiece in so many ways. Funny, witty, honest, well-researched, and genuinely life-changing in how I conceptualize how my cycle impacts my life (and how women have been systemically ignored in health and science fields). I think very few could’ve written the contents of this book better than Hill herself; she is genuine, kind, thoughtful, acknowledges limitations, and is rightfully angry, while also being cognizant of transphobic rhetoric that might emerge or sexist beliefs that women’s cyclical hormones somehow affirm the belief that we are irrational, inferior, or any other misogynistic insults. This book is fascinating, invigorating, easy to read, and is such a great call to action. Whenever someone complains about their period or related, I will be getting on my soapbox (this book) from now on.

[Vukica Bogosavljevic · Rating 4 out of 5]

The author did amazing job at explaining why and how things are happening, but there are too few offered solutions and a lot of them are simply not applicable for a lot of people. For example, yes we know that sleep important but what if it's your children that keep you from sleeping or your work includes night shift, stuff like that. Also there's a lot of repetition, literal sentences were repeated several times. in different chapters. The editor should have done a better job. Nevertheless, this book is an important starting point for future discussions.

[Nat H · Rating 3 out of 5]

Overall, this is a quick read with informative information about the menstrual cycle. At times, this book was a little repetitive. This book is heavily factual all about a woman’s cycle. Those with little to no knowledge about this topic, would be a great audience for it. The book had some great resources and information about how to improve your menstrual and overall health. I thought the book was interesting as I can relate to some of the information being summarized.

[ash · Rating 5 out of 5]

An important read. It is quite maddening to hear how medical research sidesteps women due to our cyclical nature.

As someone who already tracks their cycle to understand my “normal” this book still gave me lots of insights and ah-hah moments. I connected some dots and validated some assumptions, and gained more insight into my luteal phase.

If you’re a biological woman or care about one, read this book.

[Ciera Bohm · Rating 5 out of 5]

this book is a MUST READ. understanding our cycles and how we can best support them is such essential knowledge for all women, and honestly men too. there was some science-y bits, but this author is gifted at making it understandable for every day people. i laughed out loud multiple times, which i did not expect. 10/10 just go read it!!!

[Polly · Rating 4 out of 5]

Great and helpful information! Thought it had a nice casual and accessible writing style. Maybe a long form article could have been a better format for this one though since there is a lot a repeated information.

[Ann Beardsley · Rating 5 out of 5]

Dr. Sarah Hill brings clarity and compassion to the literal phase of the cycle. She offers understanding and helpful tips for women suffering from PMS and PMDD. Her relatable style is like getting a warm hug from your best friend who happens to be an expert in women’s health Highly recommend!

[Izzi Schieman · Rating 5 out of 5]

This is the second book I have read from Sarah and both have been extremely helpful while trying to understand my body as I transition into a new phase of my life. I would 1000% recommend this to anyone with a menstrual cycle.

[Jenna Joseph · Rating 3 out of 5]

Really good information on how the body works and why we feel the way we feel, but like a lot of “self help” books, gives very basic advice for how to feel better. I was really looking for more advice for feeling human during luteal, not just what luteal phase is.

[Jenna · Rating 3 out of 5]

I recommend this book far more than I actually enjoyed it. Her tone was pretty annoying, the advocacy stuff didn't need to be mentioned every chapter, and there were some chapters that just weren't very interesting/useful to me (I already know how to eat well). BUT it has SO much good information that women need to know and I learned quite a bit.

[rhizo · Rating 4 out of 5]

literally could not have told you anything about what progesterone does, how estrogen and progesterone cycle in a biologically female body or how progesterone affects immunology and efficacy of treatments. now i can! we call that a success story. review pending 😊

[Kristen · Rating 3 out of 5]

Helpful education and science behind something many doctors have avoided researching. I liked the practical solutions. I found the inclusive language odd for a book largely focused on science.

[Alison Spindt · Rating 5 out of 5]

This should be required reading for all 13 year old girls and then again at 18.

[Christina Knudsen · Rating 5 out of 5]

This book should be ever women’s beginners manual to their health! This was so very helpful and explained our cycles and bodies in a tangible way. The tips and advice is attainable and accessible.

[Stella · Rating 5 out of 5]

Mandatory reading for anyone who’s interacted with a girl before

[Christina Orso · Rating 5 out of 5]

Every female should read this book.