When Hormones Affect Your Mental Health: What the Research Says

Oestrogen acts directly on the brain's mood-regulating systems, including the pathways involved in emotional regulation, sleep and wellbeing. When oestrogen drops sharply in the days before a period, it can affect brain function, significantly influencing hormones and mood.

For some people, that means a mild dip in mood, but for others, the effect is significant. Understanding why is the first step to getting the right support.

Key Takeaways

• Oestrogen modulates mood-regulating systems in the brain. When it drops before a period, emotional regulation can be affected.
• Conditions including PMDD, perimenopausal depression and postnatal depression may share a common driver: the brain's sensitivity to hormonal change.
• Hormonal contraceptives affect people differently. Mood changes on the pill are real and worth raising with a doctor.
• Emerging research suggests a history of trauma may increase premenstrual mood sensitivity.
• Tracking your mood alongside your cycle for two to three months can give you genuinely useful data for a GP or specialist.
• Magnesium and vitamin B6 may support PMS mood swings, but they are not a substitute for medical care.

It Started With a Podcast

This morning, as I was scrolling through my podcast feed, looking for something to listen to while walking my dog, I landed on an episode of Hack on triple j. The topic was the contraceptive pill and I suspected the usual debate where either the pill is either seen as feminist liberation in a blister pack or as a body-hijacking toxin. But this episode was different.

The guest was Professor Jayashri Kulkarni, a Professor of Psychiatry at Monash University and The Alfred, and one of Australia's leading researchers in women's mental health. She wasn't arguing for or against hormonal contraception. She was making a different point entirely: that for too long, mental health and reproductive health have been treated as separate conversations - when for many of us, they are in fact the exact same conversation.

That podcast sent me down a research rabbit hole. And what I found genuinely changed how I think about my own cycle. If you've ever felt dismissed with a vague "it's just PMS," or noticed that your anxiety spikes reliably in the week before your period, this one is for you.

Does Oestrogen Actually Affect hormones and mood?

Yes, and there's real biology here.

Oestrogen acts on the brain as well as the reproductive system. It influences the serotonin system,  a key part of how the brain regulates mood, sleep, appetite and emotional responses. Serotonin is often called the "happy chemical," but that's a significant oversimplification. It's more accurate to think of it as part of the brain's broader emotional regulation infrastructure.

Specifically, oestrogen affects how many serotonin receptors the brain produces, supports serotonin synthesis and influences how serotonin moves between neurons. In plain terms, when oestrogen is higher, the serotonin system tends to function more smoothly. When oestrogen drops, as it does sharply in the late luteal phase, the week or so before your period, that system can be disrupted.

For many people, this shows up as a familiar low-level dip: a bit flat, a bit snappy, not quite yourself. For others, particularly those whose brains are more sensitive to hormonal shifts, the effect is more significant than a bad week. That difference in sensitivity is what Professor Kulkarni's research explores.

It's worth noting that while the oestrogen-serotonin relationship is well established in research, scientists are still mapping the exact mechanisms. This is an active area of science not yet fully researched, but the core connection between oestrogen, the brain and mood is not in question.

What Is PMDD and Is It Different From PMS?

This is one of the most common questions we get, so let's be clear about it.

PMS (premenstrual syndrome) involves physical and emotional symptoms in the lead-up to a period — bloating, breast tenderness, irritability, low mood. It's uncomfortable and can be disruptive, but most people can manage day-to-day life.

PMDD (premenstrual dysphoric disorder) is a different level entirely. It's a clinically recognised mood disorder (it's in the DSM-5, the psychiatric diagnostic manual) that causes severe depression, anxiety, emotional dysregulation and sometimes rage or despair in the one to two weeks before menstruation. Symptoms typically resolve within a few days of the start of a period, which is one of the key diagnostic clues.

PMDD is estimated to affect 3–8% of people who menstruate. It is not caused by "abnormal" hormone levels. The hormonal fluctuations in PMDD are often entirely normal. What differs is how the brain responds to those fluctuations. It's an important distinction because it changes how treatment is approached.

What Is "Reproductive Depression"?

Whilst not yet an official diagnosis, Professor Kulkarni uses the term "reproductive depression" to describe a group of mood conditions that appear to be driven primarily by hormonal fluctuation rather than the psychological or life-circumstance factors typically associated with depression. This group includes severe PMDD, postnatal depression, perimenopausal depression and mood changes linked to starting or stopping hormonal contraception.

The reason this framing matters is practical: standard antidepressants don't always work well for hormonally driven depression, because they're not addressing the actual trigger. Professor Kulkarni's team at HER Centre Australia and the Monash Alfred Psychiatry Research Centre (MAPrc) are researching treatment approaches that work directly with the hormones, including oestrogen-based therapies rather than applying a one-size-fits-all model to what are, in some cases, very different conditions.

If you've ever felt like standard mental health treatments weren't quite right for you,  particularly if your symptoms track closely with your cycle, it might be useful to bring this up in your next GP conversation.

Can The Pill Affect Your Mood?

Many people take the pill without any changes in their mood at all.

Some people find that it genuinely improves their mental health by stabilising a cycle that was making them feel terrible. 

But for some people, particularly those with an underlying sensitivity to hormonal fluctuation, oral contraceptives can produce a persistent flatness of mood, reduced libido or a sense of emotional blunting. The reason Professor Kulkarni points to is that oral contraceptives work by suppressing ovulation and keeping hormone levels more static. Whilst that prevents the sharp premenstrual hormonal crash, it also removes the natural cyclical peaks in oestrogen that support the serotonin system. For a brain that relies on those peaks, flattening the curve can flatten mood and motivation.

This doesn't mean the pill is harmful or that you should stop taking it without talking to a doctor. In fact, for people with PMDD, suppressing the hormonal cycle altogether is sometimes the most effective treatment and the pill can be part of the solution, not just the problem. The point is that different progestin types and delivery methods affect the brain differently, and "I've felt emotionally flat since I went on this pill" is a clinically relevant thing to say out loud.

If that resonates with you, it's worth having that conversation rather than assuming it's just who you are now.

Trauma, Cortisol and the Menstrual Cycle

Perhaps the most fascinating and validating part of Professor Kulkarni's work is the intersection of trauma and female biology. We know trauma lives in the body, but her research suggests it specifically hijacks the hormonal system.

Women with a history of early life trauma or complex PTSD often experience an exaggerated sensitivity to normal hormonal fluctuations. The hypothalamic-pituitary-adrenal (HPA) axis, which is the body's stress-control centre, becomes dysregulated. Because the HPA axis is closely intertwined with the hypothalamic-pituitary-gonadal (HPG) axis (which controls your cycle), a trauma-dysregulated brain will often have a severe reaction to a drop in progesterone and estrogen in the late luteal phase.

In simple terms, if you have a history of trauma and find your PTSD symptoms spiralling out of control in the week before your period, it's not in your head. It's a neurobiological interaction where your brain can't handle the drop in calming neurosteroids.

How Can We Support Ourselves?

Start tracking properly

Most of us track when our period starts. Fewer of us track mood, energy, anxiety and sleep quality across the whole cycle. Doing this for two to three months can reveal patterns that would otherwise go unnoticed. Many people discover that what they've been managing as generalised anxiety or recurring low mood actually follows a clear premenstrual arc and that's genuinely useful clinical information to bring to a GP.

Apps like Clue or Flo work well for tracking your mood over the duration of your cycle. Check out our Guide to Period Tracker Apps, or if you prefer paper-based tracking, print our paper-based period tracker, and take note of your mood alongside any other symptoms.

Consult with your doctor or find a clinician who gets it

If you've been experiencing cyclical mood changes, bring your tracking data to your GP. Ask directly about the premenstrual pattern. If you're on hormonal contraception and have noticed mood changes since starting it, say that explicitly, don't assume your doctor will connect the dots without you naming it.

Not every GP is well-versed in the intersection of hormones and mental health, so if you feel dismissed, it's reasonable to seek a second opinion or ask for a referral to a specialist in reproductive mental health. Search for a "hormone-aware practitioner" in your area, or Jean Hailes for Women's Health is an excellent starting point for finding practitioners in Melbourne or who offer telehealth consults.

Consider nutritional support during the luteal phase

There's decent evidence that magnesium and vitamin B6 can provide some support for mood-related PMS symptoms. Magnesium plays a role in nervous system regulation and may help reduce irritability and anxiety in the lead-up to a period. Vitamin B6 supports the production of serotonin and dopamine and has been studied for psychological PMS symptoms, particularly in combination with magnesium.

The evidence for both is real but modest. Neither will resolve PMDD on its own, and we'd be doing you a disservice to suggest otherwise. But as part of a broader approach, they're a reasonable place to start, especially if symptoms are mild to moderate.

Frequently Asked Questions

Does oestrogen affect serotonin? Yes. Oestrogen modulates multiple aspects of serotonin function in the brain, including receptor density, synthesis and transport. When oestrogen drops in the late luteal phase before a period, this can affect serotonin-related mood regulation. The relationship is well supported in research, though the full picture is still being investigated.

What is the luteal phase and why does mood often dip during it? The luteal phase is the second half of the menstrual cycle, from ovulation until menstruation begins, typically around 12 to 14 days. Oestrogen and progesterone both drop in the late luteal phase. For people sensitive to these shifts, this premenstrual window can bring mood changes, anxiety, irritability, fatigue and difficulty concentrating. For those with PMDD, these symptoms are severe enough to significantly disrupt daily life.

What is PMDD? Premenstrual dysphoric disorder (PMDD) is a DSM-5 recognised mood disorder characterised by severe psychological symptoms tied to the luteal phase of the menstrual cycle, typically depression, anxiety, emotional dysregulation and irritability that resolve within a few days of menstruation starting. It affects an estimated 3–8% of people who menstruate. It is caused by brain sensitivity to normal hormonal fluctuations, not by abnormal hormone levels.

Can the contraceptive pill cause depression or mood changes? For some people, yes. Hormonal contraceptives can affect oestrogen levels in ways that influence mood, sometimes producing emotional blunting, low motivation or reduced libido. Other people experience no mood changes at all, whilst others find hormonal contraception improves their wellbeing. If you notice mood changes after starting or adjusting a contraceptive, raise this with your doctor rather than dismissing it.

Is there a link between trauma and PMDD or premenstrual mood symptoms? Emerging research suggests there may be, via the interaction between the HPA (stress response) axis and the HPG (reproductive hormonal) axis. Chronic trauma can dysregulate the stress response system in ways that appear to increase the brain's sensitivity to normal premenstrual hormonal changes. Some large studies have found independent associations between PTSD, trauma history and PMDD — though the evidence is still developing, and not all studies agree.

Does magnesium help with PMS or PMDD? Magnesium has some evidence for reducing mood-related PMS symptoms, including irritability and anxiety. Combining it with vitamin B6 may enhance the effect for psychological symptoms. This may be a complementary approach, particularly for mild to moderate symptoms, but it shouldn't replace medical assessment for significant or severe symptoms.

What is reproductive depression? A clinical framework proposed by Professor Jayashri Kulkarni to describe mood disorders whose primary driver is hormonal fluctuation — including PMDD, postnatal depression, perimenopausal depression and mood changes linked to hormonal contraception. It is not yet a formal DSM diagnostic category, but it describes a real and underrecognised pattern that standard antidepressants don't always address effectively.

The Takeaway

The brain and the hormonal system are in constant dialogue. What shows up as anxiety, depression or emotional chaos might be your oestrogen and your serotonin. The most useful first step is to start tracking your mood over your cycle and talk to your GP or a specialist.

References and Further Reading

• Kulkarni J et al. "Using estrogen and progesterone to treat premenstrual dysphoric disorder, postnatal depression and menopausal depression." Frontiers in Pharmacology, 2025. View paper
• Professor Jayashri Kulkarni — Monash University research profile
• HER Centre Australia — Monash University
• Jean Hailes for Women's Health
• Triple J Hack - episode on the contraceptive pill and mental health

This article is for informational and educational purposes only and does not constitute medical advice. If you're experiencing significant mood disturbance across your cycle, please speak with a qualified healthcare professional. Period Shop sells the supplementation products mentioned in this article and has disclosed this where relevant.