Most women know only too well how their hormones impact their brain and energy levels.
Yet, if you've ever felt mentally sharp one week, or foggy and sensitive the next, your brain isn’t broken - it’s simply cycling.
Throughout our menstrual cycles, our brain chemistry shifts and changes, along with our fluctuating hormones. Our main sex hormones - oestrogen, progesterone, and testosterone - all affect mood, memory, and emotional sensitivity. Even our ability to communicate, react, focus and socialise is impacted by the ebb and flow of our hormones.
Unfortunately, these shifts can feel even more fraught and heightened as we move into perimenopause. Yet, while these changes should never feel overwhelming or impossible to navigate (if they do, you deserve support since you may be experiencing PMDD), it's important to know that this is a natural recalibration, not a malfunction.
Here's what may be happening in your brain during your cycle - and how you can support yourself.
The menstrual cycle & your brain
Week 1: Menstruation (Days 1–5ish)
At the start of our periods, oestrogen and progesterone are at their lowest levels. For most women, this can bring a sense of fatigue or inward focus - our periods are a time of physical and emotional release. Yet, for others, this phase offers relief after the turbulence of PMS.
Support Tip: Prioritise iron-rich foods, sleep, restorative rest (such as salt baths) and hydration. Let your nervous system exhale, and reflect where you can. If you feel down by period pain, prioritise reducing inflammation in the body.
Week 2: Follicular Phase (Days 5-11ish)
Here, oestrogen slowly starts to rise. You may feel your brain "switch back on" as dopamine and serotonin - two neurotransmitters that support motivation, learning, and optimism - also start to rise. It's thought that brain-derived neurotrophic factor (BDNF) rises with oestrogen, which can boost memory and neuroplasticity.
Support Tip: This is a great time for creative work, problem-solving, and setting intentions for the month ahead. At the same time, you might like to support rising oestrogen levels (and help your body in detoxifying them) with cruciferous veggies. Nourish your brain with protein, B vitamins, healthy fats, and good sleep.
Week 3: Ovulation (Days 12-15ish)
Both oestrogen and testosterone peak just before ovulation. As a result, you may feel more confident, articulate, and socially attuned. Your verbal fluency and ability to read facial expressions are also believed to improve - one reason you may find this a great time for public speaking, being assertive, or negotiating.
For those who find ovulation a struggle:
However, ovulation isn't plain sailing for everyone - if you have histamine issues, you may experience anxiety, bloating, headaches, or poor sleep. Underlying conditions, such as endometriosis, can also affect ovulation.
High oestrogen can also be stimulating. For many women, this enhances mental energy and alertness. However, for some (especially those with ADHD, sensory sensitivity, PMDD, or a history of trauma), this can tip into overstimulation, anxiety, insomnia, or irritability.
Support Tip: If you’re sensitive to the stimulating effects of oestrogen, nourish your brain’s calming pathways with magnesium, GABA-rich foods, and nervous system regulation practices. Protein and stable blood sugars are also essential.
Week 4: Luteal Phase (Days 15–28)
Here, Progesterone rises and becomes the star of the show. This hormone has a calming effect on the brain since it supports GABA. However, if oestrogen drops too quickly, or if progesterone is low (as is common in perimenopause or PMDD), symptoms like mood swings, brain fog, and anxiety can emerge.
Support Tip: This is a powerful time for intuition, reflection, and emotional processing. Support progesterone production with vitamin B6, zinc, magnesium, and stress reduction. Cut back on caffeine and overstimulation, and allow more time for stillness. If you struggle with anxiety, you might also like to try taking Saffron.
Perimenopause: The brain in transition
For many women, perimenopause brings hormonal unpredictability. Oestrogen doesn’t just decline, but it often fluctuates wildly. Meanwhile, progesterone often drops first (usually in our mid to late 30s), before staying low. The result?
You might notice:
- Brain fog or forgetfulness
- Increased sensitivity to stress or noise
- Anxiety
- Sleep disruption
- Mood swings or emotional intensity
In later perimenopause, you might start to feel foggy-headed as oestrogen drops.
Support Tip:
- Prioritise protein and blood sugar balance
- Incorporate daily nervous system support (like breathwork or gentle movement)
- Use magnesium, omega-3s, and B vitamins consistently
- Explore adaptogens, such as Naked Pharmacy's Ashwadisiac
Whether you’re bleeding, ovulating, or deep in the throes of perimenopause, your brain is adapting, recalibrating, and asking for new levels of care. With a little understanding - and more than a sprinkling of self-love and compassion - you can support your brain with more ease, clarity, and power.
Meet our guest writer! Samantha Hadadi
I’m an author (book is out this month!), women’s health and hormone coach and journalist. I’m also a mum of four boys 😊😊 
