Hormonal Isn’t Irrational: What New Progesterone Research Says About Mood and the Brain

“You’re just hormonal.”

It's a phrase many women have heard.

Sometimes as a joke.

Sometimes when they're tired, emotional, frustrated, anxious, or simply reacting to something happening around them.

And underneath it is an uncomfortable assumption:

If hormones are influencing how you feel, your feelings must somehow be less real.

But that's not how biology works.

Hormones communicate with tissues throughout the body, including the brain. Changes in reproductive hormones across the menstrual cycle can influence neural systems involved in mood, cognition, stress, and emotional processing.¹⁻³

Now, new research is adding an interesting piece to that conversation.

A 2026 study of healthy, naturally cycling women found that higher progesterone levels were associated with lower mood and differences in activity patterns within brain regions involved in emotional control.⁴

But here's the part that's especially important:

The women weren't actually worse at controlling their emotional responses.

Their brain activity looked different.

Their performance held.

Hormonal isn't irrational.

And understanding that distinction could change the way we talk about hormones and women's emotions.

First, What Is Progesterone?

Progesterone is one of the major reproductive hormones involved in the menstrual cycle.

Its levels are relatively low during the follicular phase of the cycle and rise substantially after ovulation during the luteal phase, when the corpus luteum produces progesterone.⁵

If pregnancy doesn't occur, progesterone and estradiol levels fall before menstruation begins.

But progesterone isn't only relevant to reproduction.

Progesterone and its metabolites can interact with receptors and signaling systems throughout the brain, including pathways involved in stress, mood, cognition, and emotional processing.²˒³

One particularly important progesterone metabolite is allopregnanolone.

Allopregnanolone can interact with GABA-A receptors, which are part of one of the brain's major inhibitory signaling systems. Changes in sensitivity to these neuroactive steroids have been investigated extensively in relation to reproductive mood disorders such as premenstrual dysphoric disorder (PMDD).⁶˒⁷

So the idea that progesterone might influence the brain isn't surprising.

What's more interesting is how those effects show up.

What Did the New Study Actually Find?

Researchers studied 116 healthy, naturally cycling women between 18 and 35 years old.⁴

Participants completed an emotional control task while undergoing functional magnetic resonance imaging, or fMRI.

Researchers also measured salivary progesterone and estradiol and assessed participants' recent mood.

The emotional task required participants to override an automatic emotional response.

Essentially, researchers were asking:

When emotions compete with what you're trying to do, how does the brain maintain control?

Women with higher naturally occurring progesterone showed less distinct patterns of activity in two brain areas involved in emotional regulation and motivated behaviour: the lateral frontal pole and striatum.⁴

Higher progesterone was also associated with poorer mood during the previous week.⁴

That sounds concerning until you look at what happened next.

Their Emotional Control Didn't Get Worse

This is the part worth paying attention to.

Despite differences in brain activity, women with higher progesterone were not slower or less accurate on the emotional-control task.⁴

Their performance held.

That's a very different message from:

“Progesterone makes women emotional.”

Or:

“Women can't think clearly when their hormones change.”

The study doesn't support either conclusion.

Instead, it suggests something more nuanced:

The brain may process emotional control differently under different hormonal conditions without necessarily becoming worse at it.

That's an important distinction.

Hormones Can Influence How You Feel Without Making Your Feelings Invalid

We've historically been surprisingly comfortable using hormonal biology to dismiss women's experiences.

Upset?

Hormonal.

Tired?

Hormonal.

Irritable?

Hormonal.

Emotional?

Definitely hormonal.

But identifying a biological influence doesn't make an experience less legitimate.

If anything, it gives us another reason to understand it.

Research has established that ovarian hormones interact with brain systems involved in emotional processing, stress responsivity, neurotransmission, and mood.¹⁻³

That doesn't mean hormones explain every emotional experience a woman has.

It means reproductive hormones are one part of a much larger biological system.

Your environment matters.

Your relationships matter.

Your sleep matters.

Your stress matters.

Your physical health matters.

And hormones may matter too.

Those things can be true at the same time.

“Lower Mood” Didn't Just Mean Feeling Sad

There's another interesting detail in the new research.

The study assessed mood using the Profile of Mood States, or POMS.⁴

That measure incorporates several dimensions, including:

• fatigue

• vigour

• tension

• anger

• depression

• friendliness.

So when the researchers reported an association between progesterone and “lower mood,” they weren't simply measuring sadness.

Energy was part of the picture too.

That matters because many women describe changes in energy, motivation, irritability, and emotional sensitivity across their menstrual cycle rather than simply saying they feel “depressed.”

Hormonal experiences don't always fit neatly into one emotional category.

Sometimes they show up as:

“I don't feel like myself this week.”

And that's worth taking seriously.

Does This Explain PMS?

No.

This is one of the most important limitations of the study.

Despite some headlines describing the research in the context of PMS, the researchers did not study women specifically diagnosed with premenstrual syndrome or PMDD. Pasted markdown

The participants were healthy young women without recent psychiatric diagnoses or hormonal or neurological disorders.⁴

PMS and PMDD were not measured.

So this research cannot tell us:

“Progesterone causes PMS.”

And it certainly cannot tell us that progesterone explains every mood change that happens before a period.

PMS and PMDD involve more complicated interactions between normal reproductive hormone fluctuations and individual sensitivity to those hormonal changes.⁶⁻⁸

That's a very different concept.

PMDD Isn't Simply “Too Much Progesterone”

This distinction becomes especially important when talking about PMDD.

People sometimes assume severe premenstrual mood symptoms must mean someone's hormone levels are abnormal.

Research suggests that's not necessarily the case.

Women with PMDD may have normal ovarian hormone levels but respond differently to the normal fluctuations in estradiol and progesterone across the menstrual cycle.⁶˒⁷

Research involving suppression and reintroduction of ovarian hormones has demonstrated that changing estradiol and progesterone levels can trigger symptoms in women susceptible to PMDD while having different effects in women without the disorder.⁸

So the issue may not simply be:

How much progesterone do you have?

It may also involve:

How does your brain respond when reproductive hormones change?

That's a much more useful way to think about hormone-related mood symptoms.

What About Allopregnanolone?

Progesterone doesn't act alone.

The body can convert progesterone into neuroactive metabolites, including allopregnanolone.

Allopregnanolone influences GABA-A receptors in the brain. GABA is the brain's major inhibitory neurotransmitter and plays important roles in regulating neuronal excitability, anxiety, stress responses, and mood.⁶˒⁷

Researchers have proposed that altered sensitivity to changes in allopregnanolone signaling may contribute to PMDD symptoms in susceptible women.⁶

Again, that doesn't mean:

Progesterone = bad mood.

It means progesterone participates in a complex neurobiological system, and individuals can respond differently to the same hormonal changes.

Your Cycle Isn't Just a Calendar

The new study also produced another interesting finding.

Researchers estimated menstrual-cycle phase using participants' reported cycle length.

But estimated cycle phase wasn't strongly associated with mood or the brain-activity patterns they observed.

**Measured progesterone was.**⁴

That does not mean menstrual-cycle phase doesn't matter.

The researchers themselves noted that calendar-based estimates of cycle phase are imprecise. Pasted markdown

But it highlights something worth remembering:

Your body doesn't necessarily follow a perfectly predictable 28-day graphic.

Ovulation timing can vary.

Cycle length can vary.

Hormone levels can vary between people and between cycles.

So rigid social-media rules telling every woman exactly how she should feel, eat, exercise, work, or socialize on “day 18” of her cycle can oversimplify what's actually happening biologically.

Does This Mean You Should Test Your Progesterone?

Not based on this study.

Researchers measuring progesterone in a controlled experiment is very different from recommending routine hormone testing for anyone experiencing mood changes.

This study used a single salivary hormone measurement to investigate an association between progesterone, brain activity, and mood.⁴

It was not testing a diagnostic strategy.

So the takeaway shouldn't be:

“I feel emotional, so I need a progesterone test.”

The better takeaway is:

Hormonal biology may contribute to how some women experience mood and emotional processing, and those experiences deserve to be taken seriously.

What About Hormonal Birth Control?

This study can't answer that either.

Participants were not using hormonal contraception. Pasted markdown

That's important because synthetic progestins used in hormonal contraceptives are not identical to endogenous progesterone, and different contraceptive formulations can have different biological effects.

You cannot take a finding about naturally occurring progesterone and automatically apply it to:

birth control pills

hormonal IUDs

implants

injections

or other progestin-containing contraception.

That's a different research question.

One Study Isn't the Final Answer

The study is interesting.

But it's also one study.

It was cross-sectional, meaning researchers measured hormones, mood, and brain activity at one point rather than manipulating progesterone or repeatedly following women throughout multiple cycles.⁴

That means researchers can say progesterone was associated with the findings.

They cannot say progesterone caused them.

The effect was also modest. The proposed progesterone-to-brain-to-mood pathway accounted for approximately 7% of the variation in mood in the study. Pasted markdown

That leaves plenty of room for everything else influencing how someone feels.

Sleep.

Stress.

Relationships.

Physical health.

Nutrition.

Life events.

Mental health.

Genetics.

And countless other biological and environmental factors.

Hormones matter.

They aren't the whole story.

What If Your Mood Consistently Changes Around Your Period?

Pay attention to the pattern.

Not because every mood change needs to be pathologized, but because repeated patterns are useful information.

Consider tracking symptoms prospectively across at least two menstrual cycles.

Note things like:

mood

energy

irritability

anxiety

sleep

physical symptoms

menstrual bleeding

and when symptoms improve.

Prospective daily symptom ratings are particularly important when clinicians are evaluating possible PMDD because symptoms need to show a consistent relationship with the menstrual cycle rather than simply occurring occasionally before a period.⁹

Bring that pattern to your healthcare provider.

Especially if mood changes interfere with:

work

school

relationships

daily activities

or your quality of life.

“It's hormonal” shouldn't be the end of the conversation.

It should be the beginning of a better question.

The Bigger Point: Biology Isn't a Character Flaw

Maybe the most useful part of this research isn't the exact brain region involved.

It's what the study challenges.

For generations, women's hormonal biology has sometimes been used as shorthand for being overly emotional, unreliable, or irrational.

But the new findings don't show women losing control.

They show **different neural activity occurring while behavioural performance remains intact.**⁴

Your biology can influence how you feel.

That doesn't mean your reaction is meaningless.

It doesn't mean your concerns should be dismissed.

And it certainly doesn't mean you're less capable.

Hormonal isn't irrational.

The Bottom Line

Progesterone does more than support the menstrual cycle and pregnancy.

It interacts with the brain, and growing research suggests reproductive hormones can influence neural systems involved in mood and emotional processing.¹⁻⁴

A new study found that naturally cycling women with higher progesterone had less distinct activity patterns in brain regions involved in emotional control and reported lower mood and energy.⁴

But their actual performance on the emotional-control task did not decline.

That's the part worth remembering.

The study doesn't prove progesterone causes mood changes.

It doesn't explain PMS.

It doesn't tell us anything about hormonal contraception or menopause hormone therapy.

And it certainly doesn't prove women become irrational when their hormones fluctuate. Pasted markdown

What it does give us is another reason to move beyond:

“She's just hormonal.”

Hormones can influence how you feel.

Your feelings can have a biological component and still deserve to be taken seriously.

References

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2. Barth C, Villringer A, Sacher J. Sex hormones affect neurotransmitters and shape the adult female brain during hormonal transition periods. Front Neurosci. 2015;9:37. doi:10.3389/fnins.2015.00037.

3. Sundström Poromaa I, Gingnell M. Menstrual cycle influence on cognitive function and emotion processing: from a reproductive perspective. Front Neurosci. 2014;8:380. doi:10.3389/fnins.2014.00380.

4. Buades-Rotger M, Hendricks R, Roncarati B, et al. Endogenous progesterone blurs frontostriatal representations of emotion control in healthy young women. Psychol Med. 2026;56:e263. doi:10.1017/S0033291726105315. Pasted markdown

5. Reed BG, Carr BR. The normal menstrual cycle and the control of ovulation. Endotext. Updated 2018.

6. Hantsoo L, Epperson CN. Premenstrual dysphoric disorder: epidemiology and treatment. Curr Psychiatry Rep. 2015;17(11):87. doi:10.1007/s11920-015-0628-3.

7. Hantsoo L, Epperson CN. Allopregnanolone in premenstrual dysphoric disorder (PMDD): evidence for dysregulated sensitivity to GABA-A receptor modulating neuroactive steroids across the menstrual cycle. Neurobiol Stress. 2020;12:100213. doi:10.1016/j.ynstr.2020.100213.

8. Schmidt PJ, Nieman LK, Danaceau MA, Adams LF, Rubinow DR. Differential behavioral effects of gonadal steroids in women with and in those without premenstrual syndrome. N Engl J Med. 1998;338(4):209-216. doi:10.1056/NEJM199801223380401.

9. Eisenlohr-Moul TA, et al. Toward the reliable diagnosis of DSM-5 premenstrual dysphoric disorder: the Carolina Premenstrual Assessment Scoring System (C-PASS). Am J Psychiatry. 2017;174(1):51-59. doi:10.1176/appi.ajp.2016.15121510.