Perimenopause isn’t just “low oestrogen”

Perimenopause isn’t just “low oestrogen” — why we need to look at the whole picture

If you’ve been told your perimenopause symptoms are “just hormones”, you’re not wrong… but it’s rarely just oestrogen.

Perimenopause is a transition where the body recalibrates multiple systems at once. That’s why symptoms can feel wide-ranging and sometimes confusing: mood changes, anxiety, sleep disruption, weight gain around the middle, brain fog, low motivation, cravings, fatigue, and a sense that your resilience has disappeared.

Oestrogen matters — and for many women, hormone therapy can be life-changing. But if we focus only on oestrogen, we can miss the real reason you don’t feel like yourself.

In functional medicine, we look at perimenopause as a whole-systems shift, involving:

• Stress hormones (cortisol)
• Thyroid hormones
• Progesterone
• Testosterone and DHEA
• Blood sugar and insulin
• Gut health and hormone clearance
• Sleep hormones (melatonin) and circadian rhythm
• The nervous system (your “stress response” setting)

Let’s walk through why each one matters — in plain English.

1) Cortisol: when stress starts running the show

Cortisol is your main stress hormone. It’s meant to help you wake up, handle pressure, and then wind down again.

But in perimenopause, many women find their stress system becomes more sensitive. You might notice:

• Feeling wired but exhausted
• Waking at 3–4 a.m. with a busy mind
• Feeling more anxious, shaky, or overwhelmed than you used to
• Struggling with focus, memory, or decision-making

When cortisol is out of rhythm (too high at night, too low in the morning, or high all day), it affects sleep, mood, and brain function. It can also disrupt other hormones, including thyroid and sex hormones.

If we don’t address stress physiology, you can take all the right supplements or even start hormones and still feel “on edge” or permanently tired.

2) Thyroid: the hidden driver of mood, metabolism, and brain fog

Your thyroid helps regulate energy, temperature, metabolism, and brain chemistry.

Thyroid imbalance can feel a lot like perimenopause — and it’s often missed if only TSH is tested.

Common symptoms include:

• Fatigue and low energy
• Weight gain (or difficulty shifting weight)
• Low mood, flatness, or irritability
• Anxiety, palpitations, poor sleep (in some cases)
• Brain fog and poor concentration

When thyroid hormones are not optimal, your brain can feel under-fuelled and your mood can dip. Stress can also suppress thyroid function over time.

This is why we often recommend a full thyroid panel, not a quick “tick-box” test.

3) Progesterone: your calming hormone (and often the first to wobble)

Progesterone has a calming effect on the brain. It supports GABA — one of the brain’s main “braking” systems that helps you feel settled and sleepy.

In perimenopause, progesterone can fluctuate and often declines earlier than oestrogen. That can contribute to:

• Anxiety
• Irritability
• Poor sleep and nighttime waking
• Feeling overstimulated or emotionally reactive

Many women assume they need oestrogen because they’re struggling, when actually progesterone is the missing piece (or at least part of it).

4) Testosterone and DHEA: not just “male hormones”

Women need testosterone and DHEA too.

These hormones support:

• Energy and physical stamina
• Confidence and drive
• Motivation and enjoyment
• Focus and dopamine (your reward and motivation chemical)

They can decline from our 40s onwards, and stress can push them down further.

If you’re thinking, “I don’t feel like me — I’ve lost my spark”, it’s worth looking beyond oestrogen.

5) Insulin and blood sugar: the mood and brain connection people don’t talk about

Your brain needs a steady supply of fuel. If your blood sugar is swinging, you may feel:

• Irritable, anxious, snappy
• Cravings (especially later in the day)
• Afternoon slumps
• Brain fog
• Poor sleep (blood sugar dips overnight can wake you)

In perimenopause, it’s common to become a little more insulin resistant — even if your diet hasn’t changed.

This isn’t about blame or willpower. It’s biology.

Supporting blood sugar stability can be one of the quickest ways to improve:

• Mood steadiness
• Energy
• Sleep quality
• Weight around the middle

6) Gut health: mood, inflammation, and hormone clearance

Your gut isn’t just about digestion. It influences:

• Inflammation
• The gut–brain axis (how the gut communicates with the brain)
• Neurotransmitters linked to mood
• How well you clear and recycle hormones

If you’re constipated, bloated, or alternating between loose stools and constipation, you may not be clearing hormones efficiently, and your gut may be driving inflammation that affects mood and brain function.

Sometimes the biggest breakthrough is simply getting the gut working well again — regular bowel movements, a calmer digestive system, and a diet that supports a healthy microbiome.

7) Melatonin and circadian rhythm: sleep is a hormone conversation too

Sleep problems in perimenopause aren’t always about hot flushes. They’re often about rhythm — the timing of cortisol and melatonin.

Melatonin supports sleep and has protective effects on the brain. But it can drop with:

• Stress
• Cortisol disruption
• Blue light at night (phones, tablets, late TV)
• Irregular sleep timing

Sleep disruption then worsens everything else: mood, hunger hormones, insulin, and stress tolerance.

That’s why we often start with sleep foundations before trying to “fix everything”.

8) Your nervous system: why you feel more sensitive than you used to

Many women in perimenopause describe a heightened sensitivity:

• To noise
• To stress
• To people’s demands
• To caffeine or alcohol
• To busy environments

This isn’t weakness. It’s often the nervous system running in a more activated state — and when that happens, symptoms amplify.

This is also why nervous system support (breathwork, walking, strength training done appropriately, mindfulness, trauma-informed support, social connection) can be as important as supplements.

So what does a better perimenopause plan look like?

Instead of asking only, “Do I need HRT?” we ask:

• How is your stress system functioning?
• Is your thyroid optimal?
• Are you low in progesterone, and is your brain missing its calming support?
• Are testosterone and DHEA contributing to low drive and low mood?
• Is your blood sugar stable?
• Is your gut inflamed or sluggish, affecting mood and hormone clearance?
• Is your sleep rhythm working with you or against you?

When we work on the whole picture, women often say:

• “I’m sleeping again.”
• “My mood feels stable.”
• “I can think clearly.”
• “I have energy — and patience.”
• “I feel like myself.”

A gentle reminder

Perimenopause is a real biological transition.

And you don’t have to choose between “natural approaches” and “hormones” — for many women, it’s about creating the right combination for your body, your symptoms, your history, and your goals.

If you’re struggling, the most helpful next step is usually a personalised assessment, rather than guessing.

functional medicine is a journey and this is one step along the way.

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