If you’re not familiar with her work, Cindy is a Professor of Clinical Psychology at the University of Texas at Austin, where she directs the Sexual Psychophysiology Laboratory, which is one of the only labs in the entire world devoted exclusively to studying women’s sexual health from both a psychological and a physiological angle. She is currently ranked the #1 most highly cited scholar in the world in sexual function research. She’s also the co-author of Why Women Have Sex — a book The New York Times called the most thorough taxonomy of female sexual motivation ever compiled.

In other words: if there is one person on this planet whose opinion on this topic should outrank yours, mine, and your gynecologist’s group chat, it’s her.

For nearly three decades, Cindy has been chasing a question that sounds deceptively simple: what actually drives women’s sexual desire, arousal, pleasure, and satisfaction? Turns out, a lot of what we think we know is wrong — not because anyone lied to us exactly, but because most of what passes for sex education in this country was built around a male blueprint and we all just quietly assumed it applied to us too. Here are some of my biggest takeaways from our conversation.

1. The Myth That Women Have Lower Sexual Desire Than Men

One of the most common assumptions about sexual desire is that women simply have less of it than men. The reality, according to Meston, is more nuanced (and more interesting). Women’s desire tends to be far more responsive to context than men’s. Men are more likely to experience spontaneous desire, that out-of-nowhere “I’m interested” feeling, while women’s desire tends to show up in response to what’s actually going on around them: stress, relationship quality, fatigue, body image, emotional connection. All of it.

This is both the bad news and the good news. The bad news is obvious — when life is stressful (and whose isn’t), desire can vanish entirely, and you can start to wonder if something is wrong with you. The good news is that creating the right context can bring it back, which is not something you can say about most things that go missing in adulthood. Female sexuality isn’t weaker than male sexuality. It’s just more sensitive to the conditions it’s unfolding in, which is a completely different thing, and one worth sitting with.

2. One of the Best Sexual Enhancers Might Be Exercise

This one genuinely surprised me. Research out of Meston’s lab has shown that a single bout of exercise — in one study, just 20 minutes on a treadmill(!!) — can measurably increase genital arousal in women before sexual activity. Why? Because arousal depends in part on blood flow and activation of the sympathetic nervous system, the exact same system that fires up when you exercise. Your body, as it turns out, doesn’t draw a hard line between a hard workout and... well, you can finish that sentence yourself.

Here’s the part that really got me: the effect is strongest in women whose arousal is already compromised. Her lab found it most pronounced in women reporting more sexual dysfunction to begin with, and in a separate trial, women taking SSRIs or SNRIs for depression — medications notorious for flattening sexual response — showed real improvements in desire and arousal when they exercised beforehand. So if you’re struggling with arousal, whether it’s the antidepressants, the hormonal birth control, or perimenopause doing it to you, a brisk workout before intimacy might actually help. It’s a good reminder that sexual functioning isn’t some separate, mysterious system walled off from the rest of your body. It is your body.

3. We’ve Been Defining “Good Sex” Through a Male Lens

One of my favorite moments in the interview came when we got into orgasm — specifically, the quiet assumption baked into so much of our culture that you can measure the quality of a sexual experience by whether or not a woman had one. For men, orgasm and satisfaction tend to be tightly linked, so it’s an easy metric to reach for and an even easier one to apply to everybody. But for women, Meston pointed out, the relationship is far messier and more variable than that. Some women orgasm easily. Others don’t. Some have multiple orgasms in a single encounter; others rarely have one at all. And plenty of women report deeply satisfying experiences that don’t involve orgasm in the slightest.

When we define good sex solely by orgasm frequency, we are — without really meaning to — imposing a standard built for male sexuality onto an entirely different system. A better question, and one I’ve started asking myself, is simply whether the experience felt pleasurable, meaningful, and satisfying to the person actually having it. Radical, I know.

4. Some Women Are Simply More Orgasmic Than Others

This was another good reminder that biology is doing more of the driving here than we like to admit. Women’s capacity to experience orgasm varies considerably from woman to woman, and some of that variation appears to run in families — which is a strange thing to learn about your own body secondhand from a research talk. None of this means your sexual experience is predetermined or fixed in stone. But it does mean you shouldn’t assume everyone is starting from the same baseline, because they’re not.

Too often, women compare themselves to some imagined universal standard — usually cobbled together from a movie scene, a friend’s overshare, or whatever the internet has decided is normal this week — and quietly conclude that something is wrong with them. Most of the time, nothing is. It’s just normal human variation, the same way some people are naturally deeper sleepers or have a higher pain tolerance. You wouldn’t shame someone for that. Apply the same grace here.

5. Communication Is More Important Than Technique

People go looking for the perfect technique, the perfect position, the perfect trick, as if there’s some secret move out there that unlocks great sex for everyone, every time, indefinitely. What Meston’s research consistently points to instead is something far less glamorous and far more powerful: communication. Partners are not mind readers, no matter how long you’ve been together or how well you think you know each other’s bodies. The people with the best sexual relationships tend to be the ones willing to actually talk — about what they enjoy, what they don’t, what they need, and what’s changing.

And things do change, especially as women move through different hormonal stages of life. What worked at 25 may not work at 45. What felt pleasurable before childbirth may feel entirely different afterward. What worked before menopause may not work during it. None of that is a failure to be managed quietly and alone — it’s just information. Communication is what allows two people to actually keep up with it together, instead of one person silently adapting while the other wonders what changed.

6. Sexuality Is Shaped by the Stories We Tell Ourselves

One of the concepts we got into was sexual self-schemas — essentially the set of beliefs and expectations about sexuality that each of us carries around, built up over years out of family, relationships, culture, religion, and personal history. Some schemas support healthy sexual functioning. Others quietly sabotage it without you ever clocking why. A woman who unconsciously associates sexuality with shame, obligation, fear, or guilt is going to have a fundamentally different experience than one whose beliefs are rooted in curiosity, pleasure, and connection — even if their circumstances, on paper, look identical.

The stories we carry matter more than we give them credit for. And the unsettling part is that most of us never actually chose ours. We just absorbed them somewhere along the way and started living as if they were facts.

7. Writing Can Be Surprisingly Healing

This was probably the most moving part of our conversation. In a randomized clinical trial, Meston’s lab had women with a history of childhood sexual abuse complete just five 30-minute sessions of structured writing. Some wrote about the trauma itself; others wrote specifically about how the abuse had shaped their beliefs about their own sexuality. Both groups saw real improvements in depression and PTSD symptoms — but the women who wrote about their sexual self-schema were significantly more likely to recover from sexual dysfunction altogether.

At first, this seems like an odd result. How does journaling fix something that feels so physical, so far outside the reach of a notebook and a pen? But writing helps people organize experience, process emotion, and build a coherent narrative out of things that previously felt scattered and unspeakable. In some cases, putting an experience into words appears to help women reconnect with parts of themselves that became disconnected through pain, shame, or years of quiet avoidance. It’s a powerful reminder that healing isn’t always medical. Sometimes it starts with a blank page and the willingness to be honest on it, which is a much harder thing to do than it sounds.

The Big Takeaway

If there was one overarching lesson from my conversation with Dr. Cindy Meston, it’s this: female sexuality is not simply a weaker, dimmer version of male sexuality. It operates differently — on its own terms, by its own logic. Women are not broken men. Women are women, full stop. And understanding female sexuality requires actually taking women’s experiences seriously on those terms, instead of measuring them against a standard that was never built with us in mind in the first place.

That’s a lesson that extends well past the bedroom. It’s a lesson that applies to how we study women, how we care for women, and how we understand ourselves. And it’s a big part of why I think every woman — and, honestly, every man who loves one — would get something out of this conversation.

Listen to the full conversation with Dr. Cindy Meston on The XX Lab wherever you stream podcasts or watch on YouTube.

References

For readers who want to go deeper — research discussed in this week’s conversation with Dr. Cindy Meston

Andersen, B. L., & Cyranowski, J. M. (1994). Women’s sexual self-schema. Journal of Personality and Social Psychology, 67(6), 1079–1100. https://doi.org/10.1037/0022-3514.67.6.1079

Basson, R. (2000). The female sexual response: A different model. Journal of Sex & Marital Therapy, 26(1), 51–65. https://doi.org/10.1080/009262300278641

Dunn, K. M., Cherkas, L. F., & Spector, T. D. (2005). Genetic influences on variation in female orgasmic function: A twin study. Biology Letters, 1(3), 260–263. https://doi.org/10.1098/rsbl.2005.0308

Lorenz, T. A., & Meston, C. M. (2012). Acute exercise improves physical sexual arousal in women taking antidepressants. Annals of Behavioral Medicine, 43(3), 352–361. https://doi.org/10.1007/s12160-011-9338-1

Meston, C. M., & Buss, D. M. (2009). Why women have sex: Understanding sexual motivations from adventure to revenge (and everything in between). Times Books.

Meston, C. M., & Gorzalka, B. B. (1995). The effects of sympathetic activation on physiological and subjective sexual arousal in women. Behaviour Research and Therapy, 33(6), 651–664. https://doi.org/10.1016/0005-7967(95)00006-7

Meston, C. M., Lorenz, T. A., & Stephenson, K. R. (2013). Effects of expressive writing on sexual dysfunction, depression, and PTSD in women with a history of childhood sexual abuse: Results from a randomized clinical trial. The Journal of Sexual Medicine, 10(9), 2177–2189. https://doi.org/10.1111/jsm.12247

When most people think about fiber, they think about digestion. Fruit, vegetables, psyllium husks…the unglamorous but essential stuff that keeps our bodies working the way they’re supposed to. But fiber turns out to be something more than just what our guts need. It’s something our lives need.

Let me explain.

For most of human history, the rewards that made life feel meaningful — sex, love, joy, socialization, insight, even pleasure — were wrapped in fiber. Not dietary fiber. Experiential fiber. Effort. Waiting. Uncertainty. Practice. Context. Time. Failure. The reward never came alone. It came bundled with process and friction. You didn’t get the dopamine hit of mastery without first struggling through confusion. You didn’t get the pleasure of intimacy without trust, courtship, and vulnerability. You didn’t get the satisfaction of knowledge without reading, reflecting, and integrating. You didn’t get social belonging without showing up, contributing, and being known. The reward system of the human brain evolved in a world where pleasure was inseparable from process. We had to work through the hard, undigestible bits to get the reward — and that friction, it turns out, was never incidental. It was the thing that made the reward mean something.

But now we live in an era of fiber-free rewards. Our food delivers sweetness without nourishment — ultra-processed food. Short-form content delivers stimulation without understanding — ultra-processed information. Pornography delivers arousal without intimacy — ultra-processed sex. Social media delivers attention without relationship — ultra-processed belonging. Just as fiber-stripped diets leave our bodies metabolically dysregulated, fiber-stripped experiences leave our minds psychologically dysregulated. We become restless but undernourished. Stimulated but unsatisfied. Flooded with reward signals but starved for meaning.

Here is why: the brain does not experience reward as a single event. It is a process. And it’s one that begins with anticipation, runs through effort and uncertainty, and culminates in resolution. Each stage matters. Anticipation primes the system. Effort signals that the reward is real and earned. Delay builds the neural contrast that makes satisfaction register as satisfaction rather than noise. When you strip the fiber from a reward…it becomes meaningless. You effectively short-circuit the process the brain needs to convert pleasure into something greater. The reward arrives, but the brain has no framework for it. It registers as stimulation rather than fulfillment. And when we’re not fulfilled, we reach for another one (whether its food, short-form video clips, or whatever else we’re consuming) almost immediately. This is because fiber-free rewards don’t satisfy. They amplify craving. They impair our ability to feel sated and make us chronically, mysteriously hungry.

The tragedy of modern life isn’t that we have too little pleasure. It’s that we have too much pleasure that doesn’t count. Creating a meaningful life requires fiber. This means that the solution to our current meaning crisis isn’t eliminating what makes us feel good, it’s to insist on having it delivered with the missing friction.

What does this look like in practice? It looks less like a list of rules and more like a reorientation. This means reading the long article instead of watching the video clip, cooking the meal instead of having one delivered, and working on building real relationships instead of defaulting to porn and social media use. We we should do this not because difficulty is virtuous for its own sake. Instead, we should do this because the brain was built to find meaning on the other side of effort. There are no shortcuts to the other side.

Meaning isn’t

found in the reward. It’s found in what you had to digest to get there.

Yesterday I was chatting with Dr. Natalie Crawford — whose new book The Fertility Formula comes out next month — talking about infertility.

And one of the things I kept coming back to was puzzling through the kind of infertility that makes no sense. This is the kind where all the baby-making boxes are checked…

Ovulation is happening

.
Sperm count looks good.
Hormones are normal.
Female reproductive organs in tip-top shape.

And yet… no pregnancy.

That phrase — unexplained infertility — sounds clinical. Neutral. Almost sterile.

But it’s anything but tidy when you’re living inside it. It is heartbreaking. And whenever you’re dealing with unexplained anything, it can feel beyond frustrating.

So, why do 10-30% of couples trying to conceive experience difficulty conceiving when all of the requisite parts are working? I kept thinking about something evolutionary biologists have been studying for decades… but almost never makes it into modern fertility conversations.

What if fertilization isn’t just a race between sperm to make it to the egg? What if it’s the result of a conversation? And what if, sometimes… the egg has preferences?

Evolution Didn’t Stop at Attraction

We tend to think mate choice ends before sex. You feel chemistry. You assess compatibility. You decide.

But in evolutionary biology, there’s a concept called cryptic female choice.

It’s the idea that female choice doesn’t stop at mating. It can continue after sex — inside the reproductive tract — through subtle physiological mechanisms that bias which sperm succeed.

In other words: selection can happen at the microscopic level.

And here’s where it gets really interesting.

For example, in one study, researchers found that human follicular fluid — the chemical-rich fluid surrounding the egg — differentially attracts sperm from specific men.

Not all sperm respond equally. Not all combinations behave the same. Instead, certain male–female pairings showed stronger attraction. Instead, it looked like the egg’s chemical environment responded differently depending on whose sperm it encountered (and vice versa). This is cryptic mate choice in in action, my friends.

Your Reproductive Tract Is Not Passive

Cervical mucus and follicular fluid are usually described as facilitators. They “help sperm swim.” They “signal ovulation.”

But that framing makes them sound inert. And like they’d be equally interested in welcoming all sperm to fuse into their inner membrane.

They’re not.

They contain chemoattractants — chemical signals that sperm can detect and swim toward. This process, called sperm chemotaxis, means sperm aren’t just wandering blindly. They are responding to gradients. To signals. To cues.

And those signals vary from woman to woman.

From an evolutionary perspective, that makes sense. For most of human history, reproduction wasn’t just about can you get pregnant. It was about who you get pregnant by.

Genetic compatibility matters. Immune system complementarity matters. There’s evidence in other species — and hints in humans — that fertilization may be biased toward sperm that are genetically complementary, including at regions like the major histocompatibility complex (MHC), which plays a role in immune function.

So, reproduction might not happen every time a sperm and an egg are in proximity of one another in the fallopian tube. It may also depend on things that we don’t fully understand yet, like genetic compatibility.

So Could This Explain Some “Unexplained” Infertility?

Let me be very clear here. If you are struggling to conceive, this does not mean:

• Your sex cells are “incompatible.”

• Your partner is a bad match.

• Your body is rejecting them (or theirs is rejecting you).

Fertility is complex, multifactorial, hormonal, mechanical, environmental, timing-related, and stress-sensitive. In other words, there is a whole lot more to it than “compatibility”.

Cryptic female choice is not a diagnosis or the only possible explanation for unexplained infertility. But here’s what it might be: a reminder that fertilization is more sophisticated than we once thought.

If eggs and reproductive fluids can differentially attract sperm…
If biochemical signaling plays a role in sperm guidance…
And if compatibility exists at the molecular level…

Then it’s plausible that in some cases, fertilization dynamics involve subtle signaling differences that standard tests don’t measure.

Modern fertility medicine measures count and motility. It measures structure and hormones. It does not yet measure how well two people’s gametes chemically “talk”.

The Bigger Evolutionary Picture

For most of medicine, fertilization has been treated as mechanical. But evolution doesn’t build mechanical systems. It builds selective ones. In species across the animal kingdom, females exert post-mating influence over which sperm fertilize their egg. The fact that human follicular fluid shows differential sperm attraction suggests that we may not be exempt from that biology.

This reframes something important.

Cervical mucus might not just be a fertility sign. It may be part of the selection process. And your reproductive tract may not just be facilitating sperm… it may be evaluating them. That doesn’t mean there’s a “right” or “wrong” partner. It means biology is layered. And sometimes “unexplained” just means we haven’t mapped them all out yet.

Want to Read More?

Fitzpatrick, J. L., Willis, C., Devigili, A., Young, A., Carroll, M., Hunter, H. R., & Brison, D. R. (2020). Chemical signals from eggs facilitate cryptic female choice in humans. Proceedings of the Royal Society B: Biological Sciences, 287(1937), 20200805

Firman, R. C., Gasparini, C., Manier, M. K., & Pizzari, T. (2017). Postmating female control: 20 years of cryptic female choice. Trends in Ecology & Evolution, 32(5), 368–382.

Eberhard, W. G. (1996). Female Control: Sexual Selection by Cryptic Female Choice. Princeton University Press.

Eisenbach, M., & Giojalas, L. C. (2006). Sperm guidance in mammals: An unpaved road to the egg. Nature Reviews Molecular Cell Biology, 7, 276–285.

Here’s the short version of what the vagus nerve is, why it matters for mental health, and why it may be especially relevant for conditions like PMDD and perimenopause.

First: what is the vagus nerve?

The vagus nerve is the tenth cranial nerve, and it’s one of the longest nerves in the body. It runs from the brainstem down into the heart, lungs, and gut, carrying signals back and forth between the brain and major organ systems.

Functionally, it’s a major player in the parasympathetic nervous system. This is the part of your nervous system involved in slowing heart rate, regulating digestion, dampening stress responses, and maintaining physiological balance. Researchers often talk about vagal tone, which reflects how effectively this system can regulate stress and recovery.

When vagal regulation is strong, the body is generally better at returning to baseline after stress. When it’s weaker or more erratic, stress responses can linger.

Why mental health researchers care

Vagus nerve stimulation (VNS) isn’t new. It was originally developed to treat epilepsy, and clinicians later noticed something unexpected: many patients experienced improvements in mood. That observation eventually led to FDA-approved vagus nerve stimulation for treatment-resistant depression.

More recently, researchers have been studying non-invasive vagus nerve stimulation, methods that stimulate the nerve through the skin, often via the ear. Early work suggests these approaches can influence brain networks involved in mood regulation, stress reactivity, and emotional processing.

That combination — direct nervous system access plus measurable changes in mood-related circuitry — is why this area has exploded in the research world.

Why this matters for women’s health

Women’s bodies move through profound hormonal transitions across the menstrual cycle, perimenopause, and menopause. These transitions don’t just affect reproduction; they shape stress physiology, sleep, mood, inflammation, and autonomic nervous system balance.

Research shows, for example, that hot flashes are accompanied by reductions in cardiac vagal control, suggesting that shifts in autonomic regulation are part of the picture, not just changing estrogen levels.

Conditions like PMDD are also characterized by exaggerated stress responses and emotional reactivity tied to normal hormonal fluctuations. The vagus nerve sits right at the intersection of these systems, which makes it a compelling target for understanding — and potentially improving — symptoms that have been difficult to treat well.

What we’re teaming up with OhmBody

Given all of the promise related to VNS and mental health and hormonal conditions, I recently formed a partnership with OhmBody™ to examine how non-invasive vagus nerve stimulation affects symptoms of PMDD and perimenopause. Why this particular brand? They already have peer reviewed research showing that use of their device can decrease heavy menstrual bleeding. I also have been doing research on VNS for a couple of years now, and this is the device that most closely mimics the effects of research- and medical- grade devices. I also really love their team. It's a Texas based company and they are passionate about women’s health.

Our goal is straightforward: to generate high-quality data on whether targeting this system can meaningfully shift symptom patterns in real people. This work is grounded in peer-reviewed science and designed to separate promise from hype.

As always, we’ll share what we find clearly, honestly, and with the appropriate nuance.

A quick word about hype

The vagus nerve has become a bit of a wellness celebrity. Not every product marketed as “stimulating the vagus nerve” is backed by solid evidence, and not every intervention will work for every condition. So, if you were going to use something, do a quick search to see what sort of research is behind it.

That’s why rigorous research matters. Excitement is warranted—but only when it’s paired with data.

Want to Read the Science for Yourself?

Here’s a short list of high-quality, peer-reviewed articles from reputable journals for readers who want to go deeper:

Austelle, C. W., O'Leary, G. H., Thompson, S., Gruber, E., Kahn, A., Manett, A. J., Short, B., & Badran, B. W. (2022). A Comprehensive Review of Vagus Nerve Stimulation for Depression. Neuromodulation : journal of the International Neuromodulation Society, 25(3), 309–315. https://doi.org/10.1111/ner.13528

Czura CJ, Weyand AC, Baldwin MK, Recht M, McWade MA, Covalin A, Khodaparast N. Transcutaneous auricular neurostimulation to reduce heavy menstrual bleeding in women with and without von Willebrand disease. Front Med (Lausanne). 2025 Oct 8;12:1664433. doi: 10.3389/fmed.2025.1664433. PMID: 41133152; PMCID: PMC12540315.

Hao, M., Liu, X., Rong, P. et al. Reduced vagal tone in women with endometriosis and auricular vagus nerve stimulation as a potential therapeutic approach. Sci Rep 11, 1345 (2021). https://doi.org/10.1038/s41598-020-79750-9

Rush, A. J., Marangell, L. B., Sackeim, H. A., George, M. S., Brannan, S. K., Davis, S. M., Howland, R., Kling, M. A., Rittberg, B. R., Burke, W. J., Rapaport, M. H., Zajecka, J., Nierenberg, A. A., Husain, M. M., Ginsberg, D., & Cooke, R. G. (2005). Vagus nerve stimulation for treatment-resistant depression: a randomized, controlled acute phase trial. Biological psychiatry, 58(5), 347–354. https://doi.org/10.1016/j.biopsych.2005.05.025

Thurston, R. C., Christie, I. C., & Matthews, K. A. (2010). Hot flashes and cardiac vagal control: a link to cardiovascular risk?. Menopause (New York, N.Y.), 17(3), 456–461.

It’s hard not to wonder if we’re developing social allergies.

This is an idea that I have been toying with in recent years, informed from the work I do looking at the intersection between the immune system, inflammation, and the brain (yes; I study more than hormones). Because once you understand how biological tolerance develops, you can’t help but notice the striking parallels in our social lives.

How the Immune System Learns Tolerance

So, even though I am guessing that you never spent much time thinking about your immune system, it’s really cool in about a million different super-nerdy ways. And one of those ways is the way that it learns about what cells to attack and which ones to leave along. The immune system has to learn these things because our bodies aren’t born knowing what’s dangerous and not. Instead, our immune system spends much of its time in our early life poking, tasting, sniffing, and cataloging the entire microbial world to be able to tell the difference between:

1. Things that pose serious threats to the body, and

2. Things that look like they could be dangerous, but are harmless or helpful (for example the good bacteria that line your gut)

Understanding the difference between things that can harm us and things that look harmful on the surface, but are not, is called immunological tolerance. And it’s critical. A tolerant immune system lets you pet cats, breathe near a peanut butter sandwich, go outside in spring, and generally live a happier life.

When tolerance doesn’t develop, the immune system can panic unnecessarily. Suddenly harmless pollen becomes the enemy. A peanut becomes a crisis. And a body that can’t distinguish between threat and annoyance becomes a miserable place to live. We’re talking allergies, autoimmunity, and enough inflammation to make your functional medicine doctor break out in hives.

We Need Psychological Tolerance Too

So, here is where my metaphor for the social world comes in. Because the threat detectors in human brains also need to learn the difference between what is and isn’t threatening when it comes to other people’s actions, particularly when the actions create friction. What types of things create friction? Well, to start with, different ideas, different personalities, different communication styles, and all the beautifully imperfect ways humans bump into one another.

It’s through these everyday frictions that we learn:

• Someone can disagree with us and still care about us.

• Someone can annoy us without being dangerous.

• Someone can think differently and still be a friend.

Social tolerance is what lets us stay connected even when we don’t align perfectly. It’s how relationships, neighborhoods, and democracies function.

But in the last few decades, something seems off. We seem to have lost the ability to tolerate differences. There is so much anger and fear of people who don’t share our beliefs about this topic or that. We seem to have lost sight of the fact that people can have different opinions than we have or do things that rub us the wrong way sometimes, but still be kind and have value.

So, where did things go off the rails?

Are We Growing Up in Socially Sterile Environments?

If you look at the broader culture, many of us are being raised in environments that are, metaphorically speaking, just a little too clean.

A few possibilities:

Smaller families

Siblings are like living, breathing exposure therapy. You fight, you make up, you learn that discomfort isn’t the same as danger. With fewer siblings, we may be missing that early training.

Over-parenting

Helicoptering, lawn-mowering, bubble-wrapping - whatever you want to call it - we’ve eliminated a lot of low-stakes conflict from kids’ lives. Instead of learning to resolve disagreements, kids learn that adults will swoop in before emotions get uncomfortable. This can erode our resilience to differences.

Online interaction

On screens, we lose tone, expression, and warmth. A raised eyebrow becomes hostility. A short sentence looks like aggression. Context disappears, and everything feels more threatening.

Algorithmic filtering

Social media feeds us content that agrees with us. We rarely bump into perspectives that challenge us gently and repeatedly enough to build tolerance.

In other words, we may be living through the psychological equivalent of the “hygiene hypothesis,” where protecting children from germs inadvertently creates more allergies.

When Everything Feels Dangerous

Biologically, chronic inflammation makes us more suspicious, more anxious, and quicker to perceive threat. When the body’s alarm system is turned up, the brain errs on the side of reacting, even when nothing harmful is happening.

Combine that with low real-world exposure to difference, and suddenly the mere presence of disagreement can trigger an allergic-style overreaction:

• irritation escalates into hostility

• discomfort is framed as harm

• disagreement is treated as danger

It’s not that we’re more fragile. It’s that our social tolerance hasn’t been well-developed due to lack of critical exposures.

The Cost of Losing Tolerance

When tolerance collapses, everything feels personal. We avoid conversations that matter. We unfriend instead of understand. The social fabric frays, not from grand conflicts, but from millions of tiny ones we no longer feel equipped to handle.

Innovation suffers. Relationships narrow. Communities become echo chambers.

And the world gets a little lonelier.

How We Build Tolerance Back

The good news is that tolerance is trainable. Just as the immune system becomes less reactive when gradually and safely exposed to allergens, our social systems do too.

We can start small:

• Have real, face-to-face conversations.

• Spend time with diverse groups of people with a variety of opinions about things.

• Let children navigate their own social conflicts.

• Stay curious when someone sees the world differently.

Tolerance doesn’t mean you have to agree. It means you can stay grounded while you disagree.

Discomfort Isn’t Danger

We’ve accidentally taught ourselves - and our kids - to treat irritation like injury. But in biology and in life, the ability to ignore harmless things is a superpower.

If we want a culture capable of real collaboration, we need to rebuild our capacity to sit with discomfort long enough to recognize whether there’s truly something to fear.

Because if everything looks like a threat, we’ll never stop fighting shadows.

A Final Thought

In the immune system, a little exposure to diversity keeps us healthy. In society, the same is true.

Let’s practice being in the room with people who don’t echo us perfectly. Let’s let the conversation breathe. Let’s leave space for learning, not just reacting.

Tolerance isn’t the absence of difference.
It’s the ability to stay connected in its presence.

Progestins and progesterone are not the same thing.
Not cousins. Not twins. Not even friendly look-alikes.

They’re more like the difference between stevia and sugar, instant coffee and espresso, or a spray tan and actual sunlight: similar in function only if you squint really hard and ignore what’s happening under the surface.

Let’s start with the real deal: progesterone.

Progesterone is the body’s version of the hormone.
It’s made after ovulation, in the corpus luteum (that cute little gland that shows up post-egg release like “I got you, sis”).

This hormone is a multitasking powerhouse. It:

• Calms the brain by its metabolites binding to GABA receptors (like nature’s own chill pill).

• Prepares the uterus for pregnancy.

• Reduces inflammation.

• Supports thyroid function and metabolism.

• Helps balance the effects of estrogen.

It’s one of the reasons many women feel more grounded and socially connected mid-luteal phase (and also why we feel so off when it’s too low).

Now meet her evil stepsister: the progestin.

Progestins are synthetic compounds used in hormonal birth control.

Yes: hormonal birth control does not contain progesterone. It contains progestin.

Progestins were created to mimic some of progesterone’s effects, but they’re molecularly different. Different shape, different fit, different results. They’re usually synthesized from testosterone.

Drug companies invented them in the 1950s because natural progesterone couldn’t be absorbed orally at the time, making them ineffective for use in birth control. The idea was to create something like progesterone that the body could use more conveniently.
Spoiler alert: convenience came with side effects.

Unlike real progesterone, progestins can:

• Bind not just to progesterone receptors, but also to androgen, estrogen, or glucocorticoid receptors (depending on the formulation).

• Increase clotting risk and raise blood pressure.

• Increase the risk of breast cancer when used in menopausal hormone therapy (rather than reduce it, as biologically identical progesterone paired with estradiol does!)

• Fail to deliver many of progesterone’s brain-soothing, anti-inflammatory benefits.

• Fail to provide the neuroprotective effects of progesterone.

• Fail to provide the bone density effects of progesterone.

• Destroy mood.

Some progestins act more like testosterone (hello, acne), others more like cortisol (hello, mood changes), but none replicate the nuanced effects of natural progesterone on the brain and body.

Why does this matter?

Because confusing the two has led to decades of scientific and medical misunderstanding.

When the Women’s Health Initiative (WHI) found increased breast cancer risk with “hormone therapy,” what they were actually testing was a combo of synthetic estrogen and a progestin (medroxyprogesterone acetate)—not real progesterone.

Later studies using bioidentical progesterone showed no such risk and even suggested protective effects for the brain and breasts. But that nuance got lost in translation, and women were told for 20 years that all hormones were dangerous.

Many people think that progesterone is a bad guy because progestins make them feel terrible.

Words matter. Molecules matter more.

Progesterone = the real hormone your body makes.
Progestins = synthetic imitators designed in a lab.

Calling them both “progesterone” is like calling both kale and a crouton “salad.”

So the next time someone tells you “it’s all the same,” just smile sweetly and say:

“Sure. And Velveeta is cheese.”

Further reading.

If you found yourself yelling “THANK YOU!” while reading this, you’ll love my new book, The Period Brain: The New Science of Why We PMS—and How to Fix It. It unpacks how hormonal changes shape your mood, metabolism, and mind—and how medicine’s one-size-fits-all approach has kept women feeling “off” for far too long. It’s part myth-busting, part owner’s manual for your hormonal brain, and (finally) the science women should’ve had all along. See also:

• Fournier et al., Breast Cancer Research and Treatment, 2008.

• Stanczyk et al., Fertility and Sterility, 2013.

• Prior, Endocrine Reviews, 1998.

This is the week. After years of research, writing, and rewriting, The Period Brain is finally out in the world. This book is particularly meaningful to me because I wrote it during one of the most challenging times in my life (this will be its own post sometime soon). Even though there were days when I thought I’d never be able to finish it, the mission to get this information into hands of women is what propelled me forward.

In life, when we can’t go on, we go on.

I wrote this book because so many women I know move through life feeling like their bodies are the enemy. We’re told our cycling hormones make us unpredictable. We’re dismissed as overly emotional. Our doctors often don’t understand our symptoms. Layer by layer, these messages pile up until we’re left believing we’re broken—that there’s something wrong with us. But the truth is, the only reason we’ve come to believe this is because we’ve only ever been given one version of “normal”—and that version is male.

The Period Brain rewrites this story with the latest science on women’s cycles, showing that your body was never the problem. It reveals how cycling hormones shape your brain, energy, emotions, and behavior—and how science and medicine have failed us by ignoring this entire half of the human experience.

Here are just a few of the themes you’ll find inside:

• Why PMS isn’t inevitable—and what it’s really telling us about the way women’s health has been neglected.

• The luteal phase revolution—the most understudied half of the cycle, and why unlocking its secrets is the key to feeling better.

• Progesterone: the misunderstood hormone—how it influences mood, resilience, and even our ability to overcome addiction.

• Why one-size-fits-all medicine doesn’t fit women—and what happens when you finally start working with your hormones instead of against them.

My hope is that The Period Brain will help women see themselves clearly—maybe for the first time. That it will give you the tools and the science to feel whole, rather than disordered. And that it will remind you: you were never broken. You were just never given the user’s manual.

This book is that manual. And I cannot wait for you to read it. You get your copy here today.

And you’d both be right…sort of. Decades of research show that men often outperform women on certain spatial tasks, like mental rotation puzzles or navigating by vectors (“go three blocks north, then two west”). So there is something to the whole “men are good with maps, women ask for directions’ stereotype.

But here’s the catch: change the nature of the spatial task, and suddenly the tables turn. The advantage flips. Women become expert navigators.

A farmers’ market, six snacks, and a twist

I was reminded of this paper today when I was prepping my evolutionary psychology class about sex differences in spatial memory. It describes the results of research conducted by psychologist Joshua New and colleagues to look at the nature of spatial memory. And what made this paper particularly memorable is that they did something brilliant: they ditched the abstract puzzles to test spatial memory and took to the streets. They ran their study at a real farmers’ market in Santa Barbara.

Participants were led through the stalls, sampling six foods, including things like almonds, honey, cherries, cucumbers, and the like (Yes, a psychology study where you get snacks. Where do I sign up?)

Later, standing in the middle of the market with all the stalls hidden from view, people were asked to point to where each food stall had been.

And here’s what they found: women outperformed men. And by quite a lot. On average, women were 27% more accurate at remembering where the food was.

The calories mattered, too

It turns out that women weren’t better and finding just any foods. Both men and women were sharpest at recalling the location of calorie-dense items like honey, almonds, and avocados and were less good at remembering the location of less calorie laden fare. Your brain may not care that much about the cucumbers, but it really wants to remember where the fat and sugar are hiding.

Kind of makes sense, right? For most of human history, finding the high-calorie stuff meant the difference between survival and going hungry. Your sweet tooth isn’t a modern flaw; it’s an ancient survival strategy inherited from ancestors who didn’t have an infinite number of cheap calories in bright packages to fill them at all hours of the day.

Evolution’s division of labor

Here’s the evolutionary backstory: for thousands of years, men were more often hunters, chasing mobile prey over long distances. That selected for skills like dead reckoning, vector navigation, and the classic “I don’t need a map, I know where I’m going” confidence.

Women, meanwhile, were the gatherers. Their survival - and their children’s - depended on remembering which plants were edible, which grove would fruit again next season, and which nut patch was worth revisiting. That means finely tuned spatial memory for immobile but variable resources.

So yes, men may have the edge at orienteering. But when it comes to food-location memory, women take the crown.

The modern echo

Fast-forward to now, and these ancient adaptations are still humming in the background. Ever notice you can walk into a grocery store once and instantly remember where to find that gelato that you like, while your partner swears he’s never seen it before? That’s not just a quirk. That’s your inner gatherer, alive and well.

So the next time someone teases women for being “bad with directions,” remind them: you may not know true north (or any north for that matter( but you’ll never forget where the good avocados are. And honestly? In the grand scheme of survival, that skill probably mattered more.

Let’s clear something up: Hormonal birth control (HBC) and hormone replacement therapy (HRT) are not the same thing. In fact, in many ways, they’re opposites.

What hormonal birth control does

Most forms of hormonal birth control work by shutting down your body’s natural production of sex hormones. The synthetic estrogens and progestins in the pill, patch, ring, shot, or implant suppress ovulation and blunt the rhythmic hormone fluctuations that occur across a natural menstrual cycle.

This means you’re not cycling at all. The beautiful rise and fall of estrogen and progesterone across the month—hormones that support mood, energy, libido, immune health, and metabolic function—gets turned off. Instead, you get a steady dose of synthetic hormones that override your body’s natural hormone rhythm.

And these synthetics are not the same as what your body makes. The “progestins” in birth control are often synthesized from testosterone and don’t behave like natural progesterone. They bind differently in the brain and body, and they don’t support things like mood, sleep, or bone health the way real progesterone does.

That’s one reason a lot of women feel emotionally flat, anxious, or depressed on hormonal birth control. It’s not that they’re “too sensitive” to hormones—it’s that their own natural hormones have been shut off.

What HRT does

Hormone replacement therapy—also known as menopausal hormone therapy (MHT)—does the opposite. It restores hormonal activity during the menopausal transition, when estrogen and progesterone production naturally declines.

Unlike the synthetic hormones in most birth control, HRT typically uses biologically identical hormones—molecules that are structurally identical to what the body used to make. These hormones don’t override the system; they support it. And for many women, they make a huge difference.

HRT can improve mood, sleep, libido, cognitive function, and help protect against bone loss and cardiovascular decline—issues that become more common as estrogen and progesterone taper off.

Estrogen plays a key role in maintaining bone density by inhibiting bone resorption. After menopause, the rapid drop in estrogen increases women’s risk of osteopenia and osteoporosis (Cauley, 2015). HRT has been shown to reduce fracture risk and preserve bone mineral density in postmenopausal women (Cauley et al., 2003; Gallagher, 2007).

Estrogen also has favorable effects on blood vessels and lipid profiles, which help protect against cardiovascular disease. After menopause, the incidence of heart disease in women rises sharply. When initiated early in the menopausal transition, HRT has been associated with a reduced risk of coronary heart disease and all-cause mortality (Manson et al., 2019; Hodis & Mack, 2014).

In short, HRT adds back what’s been gradually lost. It doesn’t shut the system down—it supplements it in a way that can help women feel more like themselves.

Why the confusion?

It’s easy to lump anything “hormonal” into the same bucket. But biology isn’t that simple. What matters is not just the presence of hormones, but which ones, how much, when, and why.

Hormonal birth control suppresses your natural hormone cycle. It replaces your body’s beautifully timed hormone rhythms with flat, synthetic versions designed to prevent ovulation and pregnancy. HRT, on the other hand, supplements diminished hormone levels during midlife with biologically identical hormones to support health and well-being.

They may both involve “hormones,” but they are working toward entirely different goals.

Bottom line

Saying HRT is the same as hormonal birth control because “they both have hormones” is like saying a glass of wine is the same as a blood transfusion because both contain liquid. The context, purpose, and physiological effects could not be more different.

So no, HRT is not just more hormonal birth control. It’s a different conversation entirely.

Sources

• Cauley, J. A. (2015). Estrogen and bone health in men and women. Steroids, 99(Pt A), 11–15.

• Cauley, J. A., Robbins, J., Chen, Z., et al. (2003). Effects of estrogen plus progestin on risk of fracture and bone mineral density: The Women’s Health Initiative randomized trial. JAMA, 290(13), 1729–1738.

• Gallagher, J. C. (2007). Effect of early menopause on bone mineral density and fractures. Menopause, 14(3), 567–571.

• Manson, J. E., Chlebowski, R. T., Stefanick, M. L., et al. (2019). Menopausal hormone therapy and long-term all-cause and cause-specific mortality. JAMA, 321(7), 639–650.

• Hodis, H. N., & Mack, W. J. (2014). Timing hypothesis of hormone therapy and coronary heart disease. The American Journal of Cardiology, 113(7 Suppl), 952–957.

But that conversation may be changing soon.

To start with, women’s doctors haven’t been lying to them. For a really long time now, the majority of studies that have set out to look at the relationship between hormonal contraceptive use and weight gain have found no relationship between the two. There have been some exceptions to this (I’m looking at you, hormonal contraceptive shot), but most studies fail to find a relationship between being on hormonal contraceptives and weight gain. This, of course, begs the question of why science hasn’t been able to document pill-induced weight gain when so many women report that this is what happened to them.

One possibility is that women are simply mistaking weight gained for others reasons on their birth control. It’s easy and convenient to blame our birth control for any problems we might have (although, please note that I have learned the hard way that the IRS will not accept “unusual birth control side effect” as an acceptable explanation for late taxes). So, it’s possible that women are misattributing regular, run of the mill weight gain to a birth control issue.

Another possibility is that some women *are* gaining weight on their hormonal birth control, but that science just hasn’t been able to capture it yet. This is the sort of thing that can happen when a medication impacts different people in different ways. Which of course it will. I talk about this issue a lot in my book. No two of us are built the same way, which means that each of us might respond to the exact same medication in very different ways. Especially something that influences sex hormones. This is why you should always listen to what your body is telling you. If you are experiencing a side effect that isn’t described in the package insert of your birth control, there’s a pretty good chance that you aren’t imagining things. Science probably just hasn’t been able to capture your weird side-effect yet because not everyone has it. Thankfully some new research is finally beginning to underscore this super-important point by showing gene-based differences in the risk of weight gain from the birth control implant.

In a recently published article journal Contraception, researchers found that women who went on the birth control implant (which uses the third-generation progestin etonogestrel), at the time of the study, had gained an average of seven pounds since the time it was inserted (roughly two years prior). This is significantly greater than the average two-year weight gain found among women in the absence of implant insertion. More interestingly than that, though, was what they found next. Women who had two copies of the ESR1 rs9340799 variant of the estrogen receptor gene gained, on average, gained 30.8 pounds more than all other participants after going on the birth control implant.

This is huge. And it’s huge for a couple of reasons that may be meaningful to you even if you have no intention of ever going on the birth control implant.

The first reason that these results are pretty huge is because this study found that being on the birth control implant, for all of the women in their study, was associated with an increase in weight over time. Although most women gain a little bit of weight over time, regardless of how they are preventing pregnancy, seven pounds over two years is greater than what would be expected in the absence of a manipulation (here: the birth control implant). So, the implant appears to be associated with an increased risk of weight gain for all women.

The second thing that is a big deal is that how women responded to the implant depended on their genes. Women with the ESR1 rs9340799 variant of the estrogen receptor gene were likely to gain a whole lot more weight after going on the implant that were women with other genetic variants. Like, THREE TIMES more. This is important for a lot of reasons. First, it provides evidence that women can respond very differently to the exact same type of hormonal birth control. And this includes differences in the likelihood of gaining weight from being on it. Science has finally heard you. Some women will gain weight on the pill. Some women will lose weight on the pill. And some women will experience no changes whatsoever. And one of the factors that influences which camp you will fall into is your genes.

However, the biggest deal with this is research is that it has begun to expose the tip of the iceberg. This is one genetic SNP and one type of birth control. Imagine how many unidentified risk factors for unpleasant side effects (including weight gain) each one of us has latent in our genomes. There are probably side effects that you are vastly more likely to get than others because of your genes. And there is a chance that the existing research literature – most of which doesn’t look at gene-based differences in responses to birth control at all – doesn’t yet know about it. You aren’t crazy. You aren’t imagining things. It could be your birth control.

Needing each other was normal. It was survival.

Psychologists call it fitness interdependence — the idea that your success (and your survival) was tied to the people around you.
You needed them. They needed you.
And because you needed each other, you put up with each other’s bullshit.
You forgave. You tolerated quirks. You helped even when it was inconvenient. Better yet? Because they needed you, they put up with all of your less-than-perfect qualities, too.

Fast-forward to now.
You carry a device in your pocket that gives you instant access to everything you could possibly want.

• Need a measurement conversion? Google it.

• Feeling lonely? Scroll Instagram.

• Want a date? Swipe.

• Lost? GPS it.

You don’t need anyone. Not really.

And when you don't need people, you stop trying.
You stop forgiving. You stop tolerating. You stop giving a shit.

Without fitness interdependence, relationships become optional. Disposable.
Why put up with someone’s annoying habits when you can just block them?
Why invest in messy human connection when you can order up curated entertainment on demand?

Smartphones have eaten away at the daily friction that used to bond us together.
They’ve stripped away the tiny moments of needing each other — and replaced them with the illusion of independence.

And here's the kicker:
When you no longer need other people, you become an intolerant asshole.
Lonely. Bitter. Cut off from the messy, beautiful, frustrating reality of actual human life.

We were designed to be interdependent.
Without it, we pay the price — in loneliness, in mental health, and in the slow erosion of the skills that made civilization possible.

A Google search can’t give you what a real conversation can.
An Instagram post can’t patch the hole left by a real friend.
A dating app can’t build a life with you when things get hard.

We were never supposed to do life alone.

Alone is where technology takes us.

Do we need to forgo all of our technology and move into a cave? No. This simply means that we need to be intentionally about fostering connection. Talk to your barista. Get to know the name of the man who works at the gas station. Count to ten when you’re feeling annoyed AF at the sound of your colleague’s voice. Connect, tolerate, and embrace being human.

Research conducted on heterosexual women finds that, as estrogen increases across the cycle, so too does women’s sexual desire and interest in cues of good genetic quality in men. In particular, this research finds that estrogen increases women’s preference for men whose faces, voices, and behaviors exhibit cues to the presence of relatively high levels of the male sex hormone, testosterone (we’re talking square jaws, deep voices, and swagger). This research also finds that estrogen tends to heighten women’s preference for the scent of men who possess testosterone markers and whose faces and bodies are symmetrical. Estrogen increases attention to these qualities (and makes them more desirable to women) since each of these cues are reasoned to be indicators of high genetic quality in men, which is something that would have led to more successful pregnancies and more surviving children.

So what happens to women when they go on birth control? And their levels of estrogen are kept very low. Does this suppress their preference for testosterone in men? And by doing this, does the pill affect who women are attracted to?

Given everything that estrogen does to impact women’s desire for sex and partner choice, it probably shouldn’t be hugely surprising that the pill can have some pretty sweeping effects on women’s sexual and mating psychology. But I still find this research shocking. It finds that, in addition to predicting decreased sexual enjoyment and increased risk of sexual dysfunction, the birth control pill may also affect who women are attracted to…and so so in ways that may have implications for their relationships in the long-term.

For example, in one study that was conducted on a sample of 55 women, researchers had women use a special computer program to manipulate the appearance of photographs of male and female faces. Clicking on a computer mouse allowed them to masculinize or feminize the facial prototype, which they were asked to manipulate to look like their ideal short-term or long-term romantic partner. After their first laboratory session, half of the women in their study started taking the birth control pill and the other half did not. Both groups of women came back to the lab three months later and completed this task a second time.

When the researchers compared the two sets of images created by the non pill-takers, they found no differences between the faces they created at time one and time two. However, for the women who started the pill, they found that women’s ideal male faces became significantly less masculine after the fact. A follow-up study of pill-taking women’s actual partner choice echoed these results. Using a sample of 170 age-matched, partnered women, researchers found that the faces of men who were chosen as partners by women who were on the birth control pill had significantly less masculine faces than those of their non pill-taking contemporaries.

These differences can potentially have important implications for women’s relationship satisfaction. For example, in one study conducted on 2,519 women, researchers compared ratings of relationship quality given by women who had chosen their partners when they were on the pill to those given by women who had chosen their partners when they were not on the pill. They found that women who had chosen their partners when they were on the pill reported less sexual attraction to their partners, less sexual arousal in response to their partners, and less sexual adventurousness than women who had chosen their partners when they were not on the pill. Later longitudinal studies found similar patterns. After following two samples of married couples (one sample was comprised of 48 couples; the other 70 couples) for up to five years, they found that women who chose their partners when they were on the pill and then went off of it experienced changes in sexual and relationship satisfaction in response to their change in hormonal status. Specifically, they found that all of these women reported decreased sexual satisfaction after going off the pill. And for women who were paired to unattractive husbands? They found that this change was accompanied by a decrease in overall marital satisfaction.

The results of these studies suggest that the pill – by influencing who women are attracted to – may have important implications for women’s relationships. Given that pill-taking women don’t exhibit the preference for cues to testosterone are observed in naturally cycling women, there’s a chance that a partner chosen on the pill – when women prefer rounder, more feminine faces than what is observed in non-pill-takers – may not meet a woman’s masculinity standards once she goes off the pill.

As unsettling as this interpretation may be, it is consistent with what research tells us about the effects of estrogen on mate preferences. It is also consistent with stories that I have heard from women about their transition off of the birth control pill. Although many women are able to transition off of the pill without having any major relationship disruptions, this isn’t true for others. As a research psychologist, I have had the opportunity to collect data – both in the form of surveys and interviews with women – about their experiences on and off of the birth control pill. In the process, I have spoken to several women who have had no issues with their partners whatsoever in their transition on and off the birth control pill, but also many for whom it proved very disruptive. In some, it was disruptive because they found that being off of it decreased their attraction to their partner. In others, it increased their attraction to other men. In others yet, it did both. In many of these cases, the relationship with their partners ultimately ended, which is a heartbreaking thing to have happen in response to changes in a medication.

The idea that your birth control pill might influence your choice of relationship partners in a way that that could mean trouble down the road might sound a little scary. But take heart in knowing that this doesn’t happen to all women. It’s also worth keeping in mind that relationships are always scary. The pill just adds a new wrinkle into the mix. And there is a lot that we still need to know. For example, are all birth control pills equally likely to have an impact on partner choice? And how doesthe pill impact the partner preferences and choices of women in LGBTQI+ relationships? Although there is every reason to believe that the impact of the pill on the brain should operate very similarly across people, regardless of sexual identity or orientation, we need more research to know for certain whether this is true.

Lastly, it’s worth point out that being on the pill when you choose your partner may increase your risk of some types of relationship problems, but it dramatically decreases your risk of others. For example, being on the pill decreases women’s risk of needing to get married out of financial necessity or because they got pregnant unexpectedly. It also grants women the opportunity to take their time in finding the right partner and allows them to meet their career goals and be less financially dependent on men. Both of these things increase women’s ability to find satisfying relationships. Knowing what the pill does when it comes to choosing men means that you get to choose who you want to be and what you prioritize in your partner. And that’s empowering. Whether you are on the pill or off of it, you get to pick what happens next.

In light of these criticisms and (and to test whether their product does what users say it does) 28 Wellness partnered with me and my research lab at TCU to test whether using their app, which gives women cycle-informed nutrition and fitness advice, improves health and wellness outcomes for its users. They call their approach Cycle-Based Wellness.

The First Scientific Study on Cycle-Based Wellness

Unlike generalized cycle syncing, which has been criticized for being vague, with many influencers suggesting often contradictory advice circulating on social media, 28’s Cycle-Based Wellness method is a structured daily regimen that includes phase-day specific exercises, nutrition guidance, and lifestyle recommendations based on research into how hormonal shifts affect energy, mood, and cognitive patterns.

These studies sought to determine whether following 28’s cycle-based wellness approach to fitness and nutrition resulted in improvements in:

• Mental health

• Happiness and quality of life

• Body satisfaction

• Health and fitness

• Food cravings and control over eating

• Menstrual symptoms

• Reproductive health self-efficacy (being able to determine when it is and is not necessary to visit a doctor)

Study 1: Observational Findings

The first study looked at a sample of 1,638 women who downloaded the 28 app. Users were divided into two groups:

1. Women who reported exercising in sync with their cycles using 28’s specific recommendations.

2. Women who exercised regularly but did not align their workouts with hormonal changes.

When comparing these two groups, the results revealed that women who reported exercising using 28’s specific exercise program had more favorable outcomes in almost all domains studied. The only area in which there were not consistent differences was the magnitude of menstrual-related symptoms (e.g., headaches, bloating).

These results support the idea that following 28’s fitness method leads to better outcomes in areas such as food cravings, body satisfaction, mental health, and overall quality of life.

Study 2: Long-Term Engagement and Dose-Dependent Effects

The second study was designed to narrow the focus on active users of 28’s exercise and nutrition recommendations to examine whether length of engagement with 28’s approach predicts positive changes. This study specifically measured:

• PMS

• Menstrual cycle regularity

• Period pain

• Period flow

• Happiness with how their body looks and feels

• Health

• Anxiety levels

• Energy levels

In this study (N = 446 women), results showed that women who had been engaging with the app’s exercise and nutrition recommendations for 6 months or more reported having significantly more positive outcomes on all measured variables compared to those who had used it for less than six months.

Additionally, the more that users reported following the 28 app’s nutrition and exercise recommendations, the more positive the outcomes they reported. These patterns suggest a dose-dependent effect of Cycle-Based Wellness, where women’s outcomes improved in a linear way with increased use.

Ongoing Research: Experimental Longitudinal Study

The research team is now conducting an experimental longitudinal study, tracking users (and non-users) over six months to test whether following 28’s nutrition and exercise recommendations leads to measurable improvements in women’s health outcomes over time. This will determine whether the patterns observed in the initial studies hold true under controlled conditions.

The Anatomy of Cycle-Based Wellness

28’s Cycle-Based Wellness method is built on four key components: Body Literacy, Feminine Fitness, Hormone-Focused Nutrition, and Lifestyle Guidance.

• Body Literacy: Understanding what’s happening in your body at any given time is the foundation of Cycle-Based Wellness. 28 breaks down the science behind hormonal fluctuations, their impact on the body and brain, and how women can track and interpret these changes to optimize well-being. This includes symptom documentation, cycle phase identification, and insights into rising and falling hormones.
  

• Feminine Fitness: Traditional fitness programs are built around male physiology and a 24-hour hormone cycle, failing to account for the unique needs of women, whose hormones fluctuate over a 28-day cycle. 28’s fitness method—designed by certified celebrity trainers from the Gray Institute—prioritizes low-impact, stability-based movements that optimize hormonal balance by keeping cortisol levels low and adjusting intensity based on the body's needs in each phase.
  

• Hormone-Focused Nutrition: Developed by certified functional nutritionists, 28’s nutrition philosophy shifts away from restrictive dieting and instead emphasizes nutrient-dense, unprocessed foods that deliver the key vitamins, minerals, and macronutrients needed to support hormonal health at every stage of the cycle.
  

• Lifestyle Guidance: Studies show that women’s preferences, energy levels, and cognitive patterns fluctuate throughout the cycle. 28 provides evidence-based insights and recommendations that align with these hormonal shifts to help women work with their bodies rather than against them.

The Technology Behind 28

To make Cycle-Based Wellness truly personalized, 28 developed an advanced technology platform to deliver real-time, tailored recommendations. At the core of this system is a patent-pending algorithm—the most sophisticated content recommendation engine of its kind—combined with a highly accurate phase-specific menstrual cycle tracker. This proprietary technology ensures that every user’s experience is dynamically adjusted in real time to meet their unique hormonal needs.

Does This Mean “Cycle Syncing” Works?

Maybe, maybe not. While these studies provide the first scientific evidence that 28’s specifically structured, cycle-based approach to fitness and nutrition can improve women's health, this does not validate other protocols that are cycle-aligned in nature. Various social media influencers and authors promote unvalidated protocols that lack scientific research and vary drastically in their recommendations.

28’s Cycle-Based Wellness method is different—it was built to be tested, and it is now undergoing rigorous scientific validation.

This research represents a major step forward in the scientific study of women’s hormonal health, demonstrating that when properly structured and tested, cycle-based interventions may offer real, measurable benefits for women’s well-being.

All predictions for the study and study materials are published on the open science framework here: https://osf.io/zutvp/

The working draft of the project reporting the results of the first studies can be found here: https://osf.io/preprints/psyarxiv/39rwn_v1

One of the most common birth control misconceptions that I have encountered about birth control is the myth of the locally-acting IUD. This is the belief that the hormones in the IUD “act locally”, affecting women’s reproductive organs, but not their brains. This myth is propagated by many in the healthcare profession who repeat what they’ve been told by the IUD’s manufacturers without taking the time to consider the fact that hormones don’t work that way.

Hormones - contrary to what you may have been told by a (usually) well-meaning care-giver - do not act locally.

Instead, they go everywhere in the body that blood travels. And it’s from there that hormones bind to every cell in the body that has receptors for them, many of which are in the brain.

Because of this, even though the hormone levels in the IUD are low, most women who go on it stop ovulating. At least for a little while. Here are the numbers according to the research:

• In the first year, about 65 percent of people using a 52 mg IUD won’t ovulate.

• After four years, about 25 percent of people using a 52 mg IUD still won’t ovulate (1).

Ovulation is initiated by the brain, not the ovaries. So, if the hormones were actually acting locally (again – a biological impossibility, but let’s use our imaginations), ovulation would still occur.

It’s also important to note that – even if you are ovulating on your IUD – this doesn’t mean that the hormones aren’t affecting your brain. And it certainly doesn’t mean that the hormones are acting locally. It simply means that the effects on the hypothalamus (the brain region that coordinates ovulation) are not sufficient to prevent ovulation.

So, what can you say to your doctor if (s)he suggests the hormonal IUD because it is “more natural” than other forms of hormonal contraceptives?

1. Since hormones travel through the blood stream and get everywhere that blood travels, doesn’t that mean that they will get to my brain?

2. I read that the majority of women on the hormonal IUD don’t ovulate, at least not in the first year they are on it. Since ovulation is initiated by the brain (you can specifically mention the hypothalamus if you want add style points), wouldn’t this mean that it affects the brain?

3. On average, how long does it take women to begin ovulating again once they are on the hormonal IUD? Do their side-effects begin to decrease after ovulation resumes?

4. Why do you recommend that I go on the hormonal IUD instead of using the non-hormonal cooper alternative? What are the plusses and minuses of each choice? Why do you prefer the hormonal version for me?

5. A recent study in JAMA found that the risk of subsequently developing depression was greater among women who were prescribed the hormonal IUD than it was for women who were prescribed several different types of combined oral contraceptive pills. This makes me concerned about the mental health side-effects of the hormonal IUD. Are you concerned about these side-effects for me?

You have to remember that your doctor – even when (s)he has your best interest in mind – will never care about your body and mental health the same way you do. Listen and learn from your doctor’s wisdom, but you need to be part of the conversation. Be an advocate for yourself. Ask questions. And don’t feel like you have to agree with the recommendation made by your doctor. If you don’t want to use hormonal birth control, you don’t have to. There are other options. If you are interested in using hormonal birth control, there are some options (see next paragraph) that should be less disruptive to ovulation than others. Bottom Line: YOU are the expert on your body and both you and your doctor need to respect that expertise.

Other factoids to help your convo with your doc. Hormonal IUDs are available with different doses of hormones. Higher dose IUDs impact ovulation more than lower dose IUDs (1, 2, 3). And many people using the 19.5 mg IUD continue to ovulate (4) and appear to have normal ovarian function (4). The same is true with the 13.5 mg IUD (3). If you would like to continue to ovulate while on the hormonal IUD, talk to your doctor about using a lower dose variant.

Take care. Be well. Do ridiculous things just for fun. Xoxo

But are they more natural?

First, some necessary background information. Like what a low-dose birth control pill actually is. A pill is considered low dose if it contains less than 30 micrograms (mcg) of estrogen, and those that contain 10 mcg of estrogen are considered ultra-low-dose. This is the smallest dose of estrogen available in combination birth control pills. It’s worth noting that most pills that are currently on the market are considered low- or ultra-low-dose. This includes both combination pills (estrogen and progestin) and progestin only products (which have 0 mcg of estrogen).

Given that low-dose pills (especially those that are ultra-low-dose) contain less synthetic estrogen than their higher-dose counterparts, there is a tendency to assume that they will put our body in less of an unnatural state than those containing more synthetic hormones. There is also a tendency to believe that the low-dose label means that they will be associated with fewer psychological side-effects, like changes in mood or libido. But these ideas – even though they make sense when you hear them – probably aren’t true.

Let’s start with the natural thing. Which I get. It makes good, intuitive sense that fewer synthetic hormones = less fake stuff in the body = more natural.

But it isn’t necessarily going to work this way.

To get to the heart of this, let’s talk a little about a natural cycle. Each month, women’s hormones go through a beautiful ebb and flow that is the natural result of an egg maturing and being released from an egg follicle. This includes the estrogen-dominant follicular phase, resulting from egg follicles being stimulated and eventually developing a mature ovum. It also includes the progesterone-dominant luteal phase, which is created by the temporary endocrine structure that gets created by the empty egg follicle whose job it is to release progesterone. See my picture below to see this illustrated (taken from my book). It’s an amazingly intricate act of neuroendocrinology.

Anyway.

As you can see from the picture above, women’s cycles are punctuated by a lot of hormonal activity. And these hormonal changes help to create the “natural” experience of being a woman. Peaks and valleys. Highs and lows. A dynamic experience that (in my experience) makes life feel vibrantly three-dimensional.

Now, look and see what this all looks like on the birth control pill (also taken from my book).

Above, you are seeing the levels of synthetic estrogen and progestin that are in a randomly selected version of the birth control pill (which I can do because they all work pretty much the same way). This daily dose of progestin (plus estrogen, here) creates a hormonal milieu that prevents egg maturation / ovulation and thereby suppresses women’s own production of sex hormones. So, with the pill, you experience hormonal deja vu from synthetic hormones, which prevents the release of women’s own sex hormones. So, women’s hormonal experiences are pretty much a hormonal deja vu with the message being the one that is provided by the hormones in the pill.

So, what happens with a low-dose pill?

Well, with a low dose pill, you are probably not creating a situation that is more “natural”. Instead, you are simply turning down the volume on the synthetics, leading to less (synthetic) hormonal activity in the body. Remember, women’s own hormones are suppressed**, which means the majority of sex hormonal activity going on in pill-taking women’s bodies and brains is from their birth control. This could actually feel less natural to women than the experiences created by a higher-dose pill because a typical hormonal state for naturally cycling women is one punctuated by a lot of hormonal activity.

And there is evidence that this could be the case, at least when it comes to mental health. Research on the relationship between hormonal birth control and the risk of developing depression seems to indicate the the risk is greatest for some of the products that contain the lowest levels of synthetics, in particular, non-oral products like the vaginal ring and hormonal IUD. This is far from a smoking gun (extremely far!!!), but it is worth making a mental note of the fact that low levels of hormones don’t necessarily mean that you are going to be feeling maximally like yourself. Or that you’re going to feel more “normal” or “natural” than you would with a higher dose of synthetics.

**Let me add the tentative caveat that some of our most recent research indicates that women on ultra low dose pills **may** produce relatively higher levels of their own estrogen than women on higher dose pills (although, still far less than what is created in a natural cycle). This could maybe be interpreted as being more natural and may feel more “normal” to women. We are waiting on the data telling us how these women feel… [stay tuned]. We also know that lower dose prescriptions prompt the release of fewer sex hormone binding globulins, which would make less of women’s testosterone unusable by the body. This could also be interpreted as being more natural? Although this feels a bit like splitting hairs, this could be a biologically meaningful difference in some women, making them feel more at home in their own bodies.

The big take-away, here, is that each of us should choose the dose that feels most natural to our own bodies. Because no matter what you pick – if you are on hormonal birth control – it’s going to be unnatural (see figures above). That isn’t necessarily bad. It just is. There are plenty of natural things that are terrible (SARS-CoV2, anyone?) and plenty of unnatural things that are life-saving (ventilators). So it shouldn’t be about natural. It should be about how you feel. YOU. For some women, this might mean a higher dose prescription. For others, it might mean a low- or ultra-low- dose equivalent. Tune in to your body, trust how you feel, and work with your doctor to troubleshoot your prescription. Above all else, be patient and kind to yourself. That should be the most natural thing that any of us ever do. ❤️

My mind is blown. Yet, it probably shouldn’t be. Hormones affect attraction. Decades of research has found that women’s sex hormones impact their attraction to specific members of one sex. So, why shouldn’t it also impact their attraction between the sexes? Which seems really wild, but maybe it isn’t. And if we are to take seriously the idea that gender isn’t as binary as biological sex, it really isn’t wild at all. It just goes to demonstrate that sex hormones are intimately involved in attraction and – for some women – the hormonal changes initiated by the birth control pill can nudge their preferences in ways that are more noticeable than they are for others.

The other thing that this got me thinking about was the phenomenon of mid-life sexual orientation changes. This is the thing where women who were previously only involved in relationships with men (or women), once they are in their 40s or thereabouts, start getting involved in relationships with women (or men). In other words, the gender of their preferred partners changes. I think that there is a tendency to assume that this sort of thing happens mostly in response to cultural pressures. For example, if we know a woman who was previously only involved with men who started dating women later in life, there is a tendency to assume that she was probably interested in dating women all along, but didn’t feel safe coming out as a lesbian until she was older. And there is good reason to believe that, for a lot of women, this is exactly what goes on. People who fall outside the cisgendered, heterosexual mold are still routinely discriminated against and, for many, coming out can be scary and even dangerous. But given that the hormonal changes initiated by the pill may have the ability to nudge some women’s sexual preferences this way and that, it also seems possible that mid-life changes in women’s partner choices might also occur because of mid-life changes in sexual preferences. That is, it seems pretty plausible that the mid-life hormonal changes that women experience as fertility begins to decline could nudge women’s partner preferences in ways that – for some women – produce changes in the sex of their preferred partners.

All of this is utterly fascinating to me. It raises so many interesting questions about women’s sexual psychology, attraction, and even the whole notion of the self. A person’s self – which is our perceptions about who we are – is believed to be relatively stable. But given that hormonal changes may change our self in important ways, this view of the self could actually be a totally gendered assumption that applies less to women than it does to men. That is, the idea that each of us is a relatively fixed person (and that to be otherwise is pathological or deviant in some way) may be an assumption that was created based only on the experiences of men, whose hormones change less across the lifespan. For women, it may be the norm for the self to constantly evolve. We may have many different selves instead of just one self.

I would love to hear your own thoughts on any of this. Do you know anyone who has experienced changes in sexual preferences on the pill? Has your notion of self changed in response to hormonal changes? Are our views about the self male-centric?

Xoxo. Stay healthy and be well.

Given the relaxing of restrictions that used to prevent women in their midlife from using hormonal forms of contraception, a growing number of women in their mid-30s, 40s, and 50s are finding themselves on the birth control pill. For some women, this reflects their first foray into the word of hormonal contraceptives. However, for many others, this is simply a matter of habit. They were on the pill throughout their teens, twenties, and thirties (with some taking breaks to have children). Now, they’re continuing to use it because their doctor never told them that it was time to stop or consider alternatives. This has led many women to begin wondering to themselves about whether using the pill for so long is safe and what it might be like for them once they eventually go off of it.

First, let’s talk about the benefits of midlife pill use. And there are quite a few of them. The big one is, of course, pregnancy prevention. Although the idea of a pregnancy scare can feel almost absurd to women in their 40s, unplanned pregnancies are not altogether uncommon in this age group. The reason for this is that a lot of women in this age group feel totally invulnerable to their own fertility. Somehow, the idea of getting pregnant at a time we are confronted with nearly daily reminders of our aging seems too cruel to be possible. Unfortunately, it’s not. Although women’s fertility declines as they approach middle-age, pregnancy is still possible. And the risk of complications from pregnancy and childbirth increase as women get older, women in their 40s can have a lot more to lose when it comes to unexpected pregnancies than women in their 20s. So, the pill’s pregnancy prevention effects are a huge benefit to women in midlife who are hoping to avoid the complications of an unwanted pregnancy at a time in their lives when the risks of such a pregnancy are particularly high.

There are also other perks that come from being on the pill during midlife. For example, many women find that pill use can help relieve some of the symptoms associated with perimenopause, such as cycle irregularity and hot flashes. Combination pills containing both estrogen and progestin seem to offer women the greatest symptom relief. These symptoms occur because of hormonal imbalances that can occur across the cycle as women age. The pill – because it keeps women’s own levels of sex hormones low and replaces them with a consistent daily dose of synthetic hormones – can help manage these symptoms. Although the pill does not address the cause of these symptoms (it does not address any of the underlying issues that create the hormonal imbalances at the root of these symptoms), it can provide women relief from them.

The pill has also been found to offer symptom relief to women who experience severe PMS or PMDD (premenstrual dysphoric disorder – a more serious form of PMS). PMS and PMDD symptoms – which manifest themselves as a combination of physical and psychological effects, such as mood changes, irritability, and physical discomfort – are believed to be caused by abnormal physiological responses to changing levels of hormonesacross the cycle. By ironing out the hormonal fluctuations that occur across the cycle and lifespan, the pill can take the edge off PMS for women whose brains and bodies don’t respond well to hormonal ups and downs. This is particularly true of brands that use the same dose of hormones throughout the cycle (monophasic treatments) or those that keep you on a steady dose of hormones for three months before you have your week of placebo pills. Estrogen containing pills are also known to reduce women’s risk of endometrial and ovarian cancer, and may even offer some protection against colon cancer.

Now, for the drawbacks. Although research consensus tells us that midlife pill use is perfectly safe for most healthy, nonsmoking women 35 and older, it’s not for everyone. It can still be associated with an increased risk of serious cardiovascular events (like strokes and heart attacks) in women who smoke, are obese, or have a personal health history that is known be associated with an increased risk of cardiovascular events (e.g., migraine with aura or diabetes). It is generally recommended that these higher-risk women avoid estrogen containing products, since estrogen use is linked with an increased risk of cardiovascular events; however, progestin only formulations canoften be safely. You will need to talk with your doctor about whether it makes sense for you, given your unique personal and health history.

It’s also worth noting that we don’t yet know a whole lot about what it means for women to be on a more-or-less steady dose of hormonal contraceptives for decades at a time. How does this change women’s bodies? And brains?

There is a growing body of research in psychology and neuroscience that finds that the birth control pill can number of effects of the activities of the brain. For example, research indicates that the pill can influence the psychological processes involved in sexual attraction and partner preferences, the desire for sex, the nature of the stress response, learning and memory, mood, suicide risk, and learning and memory. Accordingly, women of all ages on the birth control pill will want to keep track of how they are feeling, psychologically, as well as physically to determine whether the birth control pill is the right choice for them. Keeping a journal of your physical, as well as psychological, symptoms before and after starting hormonal contraception can be a useful tool to help determine whether birth control pill use is right for you.

Although birth control use is a safe and effective means of regulating fertility for healthy women 35 and over, it is important to understand that there are questions that still remain. For example, we don’t know whether women 35 and over need the same doses of hormones needed by younger women to regulate fertility. We also don’t know what doses of estrogens and progestins are least likely to cause cardiovascular or metabolic issues, which tend to be of greater concern to women 35 and over.

Women in midlife need to be proactive about regulating their fertility up until they have stopped having menstrual cycles for two years or reach age 55, when natural sterility is assumed. If you are a healthy non-smoking woman, the birth control pill can be part of this strategy until birth control is no longer needed.

Hormonal birth control has revolutionized society by allowing women to decide when they want to have children. This power has given women more freedom than they have ever had. But changing a woman’s sex hormones with the pill also means changing a woman’s brain, and that changes everything about her and around her. Here are just a few examples of what the research suggests.

PARTNER: Estrogen leads to a heightened preference for sexy men. Sexy men = good genes = healthy children. But the pill suppresses ovulation, which means it also suppresses estrogen. This can cause pill-taking women to choose partners for reasons other than physical attraction (like financial fitness). That may be a plus, but it also means there’s a risk that going off the pill means finding out you are not attracted to the partner you chose while on it.

SMELL, SMELL, SMELL: Naturally cycling women literally (if unconsciously) detect a man’s genetic quality by the way he smells. But the pill blunts women’s sensory acuity making make them unable to tell the difference between men who are a good genetic match and men who aren’t. Turning smell around, the scent of naturally cycling women varies through the month, with the fertility signal being most attractive to men. The pill suppresses these signals.

SEX! Women on the pill have lower sexual desire than naturally cycling women. They have sex less frequently and are more likely to experience discomfort. This may result from the suppression of ovulation and its accompanying hormone surge.

STRESS! Women on the pill have a blunted free cortisol response to stress, which sounds great (no stress, yay!), but makes it harder for the brain to grab on to the emotionally complex moments in our lives. When nothing is being flagged as a threat or an opportunity, women can start feeling their world is a little . . . flat. They may also have trouble learning and remembering.

INFLAMMATION: Cortisol helps the body regulate inflammation. With a blunted stress response, pill-taking women are at greater risk of developing autoimmune conditions; in fact, 78% of people suffering from autoimmune diseases are women.

MOOD: The pill affects many neurotransmitters, particularly those associated with reward and pleasure, in ways that can mean trouble for mental health. It’s important to know your family’s history of mental illness and reactions to the pill, and to let someone close to you know you’ve started a new pill so they can note any changes in behavior.

MOTIVATION–HERS AND HIS: Women on the pill are attaining higher levels of education and achievement in fields previously closed to them, like law, medicine, science, government, and business. Interestingly, though, the pill may have the opposite effect on men, since they no longer need to fight as hard to prove themselves worthy of sex.

THE TAKEAWAY: make an informed decision. Weigh the pros and cons. Check out the different varieties of birth control available. This way you can always be the version of yourself you most want to be.

Read more in my book. Get the book.

Subscribe now