Something I hear all the time from women in their early to mid-forties is some version of the same thing: I do not feel like myself, but I cannot put my finger on why. The sleep is different. The energy is different. The mood, the motivation, the way their body responds to food and exercise — it has all shifted, sometimes subtly, sometimes dramatically. And when they go looking for answers, what they tend to find is a conversation that revolves almost entirely around one hormone: oestrogen.
Oestrogen matters. There is no question about that. But if you want to understand what is actually happening in perimenopause — and more importantly, what to do about it — you need to look much further than a single hormone. The changes happening in your body right now are systemic. They involve your entire hormonal network, your nervous system, your metabolism, your mitochondria, your gut, and your immune system. And the sooner you understand that, the sooner you can start making decisions that genuinely support how you feel.
This article is going to walk you through what perimenopause actually is, what is driving the symptoms you are experiencing, and why a whole-body, systems-based approach is the most intelligent way forward.
Perimenopause Is Not a Single Event
One of the biggest misconceptions about perimenopause is that it is a short, well-defined window of time. In reality, perimenopause is a transition that can span anywhere from four to twelve years. It typically begins in the early to mid-forties, though for some women it starts in the late thirties. And it unfolds in stages, each with its own hormonal signature and its own set of potential symptoms.
In the earliest phase, your menstrual cycle may shorten slightly. You might notice cycles dropping to 25 or even 21 days, or you might experience heavier periods, increased breast tenderness, or a new intensity to premenstrual mood symptoms. These early changes are often subtle enough to dismiss, but they are significant. They signal that the hormonal conversation in your body is already shifting.
As the transition progresses, cycles become more erratic. You might skip a period one month and then have a very heavy one the next. Ovulation becomes less consistent, and with it, the hormones that depend on ovulation — particularly progesterone — become less reliable. In the later stages, you may go 60 or more days without a period, experience more pronounced symptoms like hot flushes, night sweats, sleep disruption, and brain fog, and feel as though the ground beneath you has shifted in a way you cannot quite control.
Menopause itself is a single point in time: it is the day that marks 12 months since your last period. Everything before that is perimenopause. Everything after is postmenopause. But the experience of this transition is anything but a single moment. It is a process, and understanding where you are in that process changes how you approach your health.
It Starts with Progesterone, Not Oestrogen
This is perhaps the most important thing most women are not told: the first hormone to change in perimenopause is not oestrogen. It is progesterone.
Progesterone is produced after ovulation. When you ovulate successfully, your body produces a healthy amount of progesterone in the second half of your cycle. But as you move into your late thirties and forties, ovulation becomes less consistent. Some months you ovulate, some months you do not. And in the months where ovulation does not happen — known as anovulatory cycles — your body produces very little or no progesterone at all.
This matters enormously, because progesterone does far more than support pregnancy. It has a calming effect on the brain and nervous system. It supports sleep, helps regulate mood, and plays a role in reducing inflammation. When progesterone drops while oestrogen remains relatively high, you get a pattern sometimes referred to as oestrogen dominance — not because your oestrogen is necessarily too high in absolute terms, but because it is unopposed by adequate progesterone.
This imbalance is responsible for many of the earliest perimenopause symptoms: heavier periods, increased period pain, breast pain, new or worsened migraines, sleep disruption (particularly waking in the early hours), heightened anxiety, and mood swings that feel disproportionate to what is happening in your life. If any of this sounds familiar, it is likely that progesterone is already part of your story.
Oestrogen Does Not Simply Decline. It Fluctuates!
The popular narrative around menopause is that oestrogen gradually declines and then stops. The reality is far more complex. During perimenopause, oestrogen levels do not follow a smooth downward curve. They fluctuate — sometimes dramatically. You can have days or weeks of very high oestrogen followed by a sharp drop, and it is the volatility itself that causes many of the most disruptive symptoms.
Your brain, in particular, struggles with these swings. Oestrogen is deeply involved in regulating serotonin, dopamine, and other neurotransmitters that affect mood, motivation, cognition, and sleep. When oestrogen levels are stable, these systems function well. When oestrogen swings from high to low unpredictably, it can trigger anxiety, irritability, brain fog, insomnia, and a sense of emotional instability that many women find deeply unsettling.
Hot flushes and night sweats are also driven by oestrogen fluctuation rather than simply low oestrogen. The thermoregulatory centre in your brain becomes more sensitive to small shifts in hormone levels, narrowing the window within which your body feels comfortable. A sharp drop in oestrogen can trigger a flush response even when overall levels are not particularly low.
This is why a single blood test for oestrogen in perimenopause is often not very useful. A snapshot taken on one day tells you almost nothing about the broader pattern. Your levels could be high one week and low the next. Understanding that the pattern is one of fluctuation — not a simple, steady decline — changes how you interpret your symptoms and how you think about support.
Beyond Oestrogen and Progesterone: The Bigger Hormonal Picture
Oestrogen and progesterone are central to the perimenopause story, but they are not the only hormones in play. Testosterone, DHEA, cortisol, insulin, thyroid hormones, and melatonin are all part of the picture, and changes in one area inevitably affect the others.
Testosterone, for example, declines gradually throughout a woman’s life, but the effects often become more noticeable in midlife. Lower testosterone can contribute to reduced motivation, lower libido, decreased muscle mass, and a general sense of flatness or loss of drive. Many women describe feeling like they have lost their spark — and testosterone may well be part of that equation.
Cortisol deserves particular attention. As oestrogen and progesterone become less reliable, your body increasingly leans on the adrenal system. The hypothalamic-pituitary-adrenal axis — your central stress response system — can become more reactive during this time. If your stress load is already high (and for most women in midlife, it is), the added hormonal instability can amplify the stress response, creating a cycle of cortisol dysregulation, poor sleep, increased inflammation, and further hormonal disruption.
Thyroid function is another area that frequently overlaps with perimenopause. The symptoms of underactive thyroid — fatigue, weight gain, brain fog, hair loss, low mood, constipation, feeling cold — look remarkably similar to perimenopause symptoms. And to make things more complex, fluctuating oestrogen can directly affect thyroid hormone availability by increasing levels of thyroid-binding globulin, which reduces the amount of free thyroid hormone your cells can actually use. This means some women need their thyroid medication adjusted during perimenopause, and others may develop thyroid issues for the first time.
Then there is insulin. Declining oestrogen affects how your body handles glucose and responds to insulin, increasing the risk of insulin resistance in midlife. This shows up as stubborn weight gain (particularly around the middle), energy crashes, increased cravings, and difficulty losing weight despite doing everything you used to do. We will explore this in much more detail in a separate article, but for now, know that metabolic health is deeply intertwined with hormonal health.
Your Symptoms Are Connected, Not Random
One of the most frustrating aspects of perimenopause is how disconnected the symptoms can feel. You might be dealing with poor sleep, anxiety, digestive changes, joint pain, skin dryness, brain fog, and weight gain all at once, and it can feel as though your body is falling apart in unrelated ways.
But these symptoms are not random. They are connected through the systems that oestrogen, progesterone, and the broader hormonal network support. When these hormones shift, they affect neurotransmitter function (which influences mood, cognition, and sleep), immune regulation (which can increase inflammation and histamine reactivity), gut health (oestrogen plays a direct role in the gut microbiome and intestinal lining), mitochondrial function (your cellular energy production), and cardiovascular regulation (which affects everything from blood pressure to palpitations to temperature control).
Understanding that your symptoms are part of a connected pattern — rather than a collection of separate problems — is one of the most empowering shifts you can make. It means you do not need a different solution for every symptom. What you need is a strategy that addresses the underlying systems driving those symptoms.
Why a Whole-Body Approach Matters
This is at the heart of everything I believe about health in midlife: no single hormone, no single supplement, and no single intervention is going to address the full picture of what is happening in perimenopause. The body is an interconnected system, and the changes you are experiencing reflect shifts across multiple systems at once.
That is why a whole-body, systems-based approach is so important. Instead of chasing individual symptoms, it means looking at how your hormones, your metabolism, your stress physiology, your gut health, your nutrient status, your sleep architecture, and your inflammatory load all interact. It means understanding that addressing cortisol might improve your sleep, which in turn supports better insulin sensitivity, which then makes it easier for your body to manage hormonal fluctuations.
It means recognising that what you eat, how you move, how you manage stress, and how you sleep are not peripheral to your hormonal health — they are central to it. And it means being willing to look deeper when something does not add up, rather than accepting a surface-level explanation.
What You Can Do Right Now
If you are in the early stages of perimenopause, or if you suspect you might be, here are some things worth considering as a starting point.
First, track your symptoms and your cycle. Patterns become visible over time that are invisible on any given day. Notice what changes, when it changes, and what seems to make things better or worse. This information is incredibly valuable, both for your own understanding and for any practitioner you work with.
Second, prioritise protein and blood sugar balance. Many perimenopausal symptoms — energy crashes, cravings, mood swings, poor sleep — are worsened by blood sugar instability. Eating adequate protein at every meal, pairing carbohydrates with protein or healthy fats, and reducing your reliance on sugar and ultra-processed foods can make a meaningful difference.
Third, address your stress load. This is not about bubble baths and scented candles (though those are lovely). It is about genuinely evaluating your nervous system state. Are you in a chronic state of high alert? Is your body getting enough signals of safety — through sleep, through rest, through time in nature, through connection? Your hormonal system cannot regulate itself effectively when your nervous system is stuck in overdrive.
Fourth, do not accept a one-size-fits-all answer. If a practitioner is dismissing your symptoms, running minimal tests, or offering a single solution without investigating the broader picture, you are allowed to seek a different level of care. You deserve someone who is willing to look at all the systems involved, not just one.
And finally, know that this transition, while challenging, is not a decline. It is a recalibration. Your body is moving into a new phase, and with the right understanding and support, that phase can be one of clarity, strength, and vitality. The goal is not to go back to how things were. It is to move forward with intelligence, with strategy, and with the knowledge that what is happening in your body makes sense — and that there is a clear path forward.