Hot flashes, brain fog, broken sleep, vanishing motivation. These are not random. They are the predictable result of three hormones doing something very specific. Here is what that looks like.
In the last post in this series, we talked about what perimenopause is, when it starts, and why so many women arrive at it completely unprepared. This post goes one level deeper: the hormones themselves. Because once you understand what estrogen, progesterone, and testosterone are doing in your body, and what happens when they stop doing it reliably, the symptoms of perimenopause stop feeling random and start making complete sense.
That shift, from confusion to comprehension, is one of the most powerful things education can offer a woman going through this transition. It does not make the symptoms disappear. But it removes the fear that something is fundamentally wrong with you, because the answer is that nothing is wrong. Your body is doing exactly what it is supposed to do. It is just that nobody told you it was coming or educated you on what is happening and why. Because understanding what is happening is the first step toward understanding what can help it.
Estrogen, Progesterone, and Testosterone: The Three Hormones You Need to Understand
| Hormone | What it does when levels are healthy | What happens when it declines |
| Estrogen | Regulates body temperature; protects bone density and cardiovascular health; supports brain function, memory, and concentration; stabilizes mood via serotonin regulation; maintains skin hydration and elasticity; supports bladder and urinary tract health; and drives the menstrual cycle. | Hot flashes and night sweats (affecting up to 85 percent of women); accelerated bone density loss leading to osteoporosis (one in two women over 60 have low bone mass); significantly increased cardiovascular risk (heart disease is the number one killer of women after menopause); brain fog and memory lapses; mood instability and heightened emotional sensitivity; vaginal dryness and painful intercourse (affecting at least 50 percent of postmenopausal women); joint pain; skin thinning and dryness; bladder urgency and increased urinary tract infections; and for women with severe vasomotor symptoms, a 1.5-fold increased risk of coronary heart disease and stroke. |
| Progesterone | Balances estrogen, promotes deep restorative sleep, calms the nervous system via the GABA pathway, regulates the menstrual cycle, and acts as a natural antidepressant and anti-anxiety agent. | Sleep disruption and night waking, increased anxiety, panic attacks, mood swings and emotional sensitivity, depression, heavier or irregular periods, heightened stress reactivity, and for women with a prior history of anxiety or depression, a significant worsening of those conditions. |
| Testosterone | Supports energy and stamina; drives libido and sexual satisfaction; maintains muscle mass and strength; protects bone density; powers motivation, drive, and ambition; supports cognitive sharpness, memory, and concentration; and contributes to emotional resilience and overall sense of wellbeing. Women produce roughly three times more testosterone than estrogen before menopause. | Persistent fatigue that sleep does not fix; significantly reduced or absent libido (affecting 50 percent of menopausal women); loss of muscle mass and strength; difficulty maintaining a healthy weight; reduced motivation and drive, including loss of ambition at work; brain fog and difficulty concentrating; mood changes including irritability, flat affect, and depression; hair thinning; bone density loss; reduced confidence and emotional resilience; and a general sense that the drive for life has quietly disappeared. |
Estrogen: The One That Changes Everything
Estrogen is the hormone most people associate with menopause, and for good reason. It has receptors throughout virtually every system in the body, including the brain, heart, bones, skin, bladder, and gut. When estrogen levels are stable, many of those systems run quietly in the background without drawing attention to themselves. When estrogen starts to fluctuate and decline, they make themselves known.
The most dramatic statistic in this area is the scale of the decline. As women transition through menopause, estradiol levels, the primary active form of estrogen, drop by more than 80 percent. That is not a subtle shift. It is a fundamental change in the hormonal environment that the body has operated in for decades, and it explains why the symptom list is so wide-ranging. Hot flashes and night sweats affect up to 85 percent of postmenopausal women and are the direct result of estrogen’s role in regulating body temperature. Bone density loss accelerates significantly once estrogen withdraws its protective effect. Cardiovascular risk rises. The brain, which relies on estrogen for neuroprotection, becomes more vulnerable, which is part of why researchers are increasingly studying the link between the menopause transition and later Alzheimer’s risk in women.
What makes perimenopause particularly disorienting is that estrogen does not simply decline in a straight line. During the transition, it fluctuates wildly, surging and dropping in ways that can feel completely unpredictable. A woman might have a good week followed by a terrible one, not because her symptoms are imagined or inconsistent but because her estrogen levels genuinely are.
There is also a knock-on effect that extends well beyond estrogen’s direct role. Estrogen plays a significant part in regulating dopamine, serotonin, and cortisol, the hormones and neurotransmitters that govern mood, motivation, stress response, and the ability to feel pleasure. When estrogen fluctuates, it pulls these systems out of balance too, which is why anxiety, low mood, and difficulty handling stress are so common during perimenopause and so frequently misattributed to something else entirely. We will cover this in detail in the next post in this series.
Progesterone: The Calming Hormone Nobody Talks About
Progesterone is often described as estrogen’s counterbalance, and in the context of perimenopause, it is the hormone that tends to drop first and fastest. It is produced primarily after ovulation, so as ovulation becomes less frequent and eventually stops, progesterone levels fall significantly before estrogen does the same.
The consequences show up most clearly in two areas: sleep and anxiety. Progesterone has a calming, sedative effect on the nervous system. When it is present in healthy amounts, it supports the kind of deep, restorative sleep that makes everything else manageable. When it drops, many women find themselves waking at 3 or 4 in the morning, unable to return to sleep, not because of a sleep disorder but because the hormone that was helping them stay asleep is no longer there at the levels it once was.
When I talk to women about their early perimenopause symptoms, broken sleep is almost always the first thing they mention. They describe lying awake for hours, minds racing, wondering what is wrong. Often nothing is wrong with their sleep specifically. Their progesterone has simply dropped below the level needed to support it. That single piece of information changes how a woman understands and approaches what she is experiencing.
The mental health effects of declining progesterone go well beyond low mood and deserve to be named clearly. Progesterone regulates the GABA system, the brain’s primary calming pathway. When progesterone drops, GABA activity drops with it, which is why anxiety in perimenopause can escalate from background unease to full panic attacks. Between 40 and 50 percent of perimenopausal women report significant mental health symptoms, often describing them as similar to PMS but more intense and unpredictable. Women with a prior history of anxiety or depression are at particular risk of experiencing a marked worsening during this transition.
Lower progesterone also amplifies the stress response. Women who previously handled pressure with relative ease can find themselves feeling overwhelmed, emotionally reactive, or unable to recover from difficult moments the way they once did. They are not becoming less capable. They are operating with less of the hormone that kept their nervous system regulated, and that is a physiological reality, not a personal failing.
Testosterone: The Forgotten Hormone in Women’s Health
Testosterone is rarely part of the conversation when women and their doctors discuss menopause, and that omission has real costs. Women produce testosterone in their ovaries and adrenal glands throughout their lives, and it plays a significant role in energy, motivation, cognitive sharpness, muscle strength, bone density, and libido. Testosterone levels in women can be as much as 50 percent lower in menopause compared with younger years, and the effects are often mistaken for depression, burnout, or simply getting older.
The workplace implications of declining testosterone are worth naming directly. The fatigue that makes a full day feel like a marathon. The difficulty sustaining motivation on projects that would previously have felt energizing. The sense that the mental sharpness that once came naturally now requires deliberate effort. These are not character failings or signs of disengagement. They are the predictable result of a significant hormonal shift that most women have never been told to expect.
Research is increasingly supporting testosterone therapy as an addition to standard hormone treatment for women experiencing these symptoms, particularly around mood, motivation, memory, and libido. It is not yet widely prescribed in Canada, but awareness is growing, and it is worth raising with a knowledgeable healthcare provider.
Why the Dimmer Switch Analogy Actually Works
The most useful way I have found to explain what happens to hormones during perimenopause is to imagine a dimmer switch rather than a light switch. A light switch goes from fully on to fully off in a single movement. A dimmer switch turns down gradually, but it does not do so smoothly. It flickers. It brightens unexpectedly. It dims again. Sometimes it stabilizes for a while before dropping further.
That is perimenopause. The hormones are turning down, but they are doing it inconsistently, which is why symptoms can feel so erratic. A woman might feel completely like herself for two weeks and then spend the following week wondering what happened. Nothing happened, except that her estrogen or progesterone moved in a direction it was always going to move, just on its own unpredictable schedule.
Understanding this does not make the dimmer stop flickering. But it does mean that when the light changes, you know what you are dealing with and you know where to look for help.
What This Means Practically
Knowing your hormones does not require a medical degree. It requires enough information to recognize what you are experiencing, to connect the dots between a symptom and its cause, and to walk into a conversation with a healthcare provider or an HR leader with confidence rather than confusion.
If you are experiencing sleep disruption, look at progesterone. If you are experiencing hot flashes, brain fog, joint pain, or mood instability, look at estrogen. If you are experiencing persistent fatigue, loss of motivation, or a noticeable drop in drive that does not respond to rest, ask about testosterone. These are not vague feelings or signs of weakness. They are hormonal signals with known causes and, in most cases, with real options for support.
Hormone replacement therapy is one of the most effective and well-researched options available for managing the symptoms described in this post, and Menovate fully supports informed access to it. That said, HRT is not the right path for every woman. Some cannot take it due to personal or family medical history, including hormone-sensitive cancers, blood clot disorders, or cardiovascular conditions. Others may choose not to, and that is a completely valid decision. The goal of naming hormones is not to funnel every woman toward a single solution. It is to give every woman enough knowledge to have an informed conversation with her healthcare provider about what is right for her specifically.
HRT is also not the only option available. There are non-hormonal prescription medications that can help with specific symptoms such as hot flashes, sleep disruption, and mood. Lifestyle changes, including targeted nutrition, sleep habits, exercise, and stress management, have well-documented effects on how the body experiences the menopause transition. And for many women, a combination of approaches works better than any single one. We will go deeper on all of this in the posts ahead.
The next post in this series will cover those options in detail. Post 4 looks at the knock-on hormones: what estrogen’s decline does to dopamine, serotonin, and cortisol, and why so many symptoms get misattributed to stress or mental health conditions rather than perimenopause.
Later posts in the series will go deep on non-hormonal medical options for specific symptoms, and the lifestyle changes, nutrition, sleep, exercise, and stress management that have the strongest evidence behind them for supporting your body through this transition. Because how you live has a measurable impact on how you experience this. And that is information every woman deserves to have.
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Aimee Debow is the Founder of Menovate and a certified Menopause Coach. Menovate helps Canadian organizations build menopause-supportive workplaces through corporate talks, e-learning, and HR advisory services. Learn more at menovate.ca.
Sources: PMC, Estrogen Deficiency in the Menopause and the Role of Hormone Therapy, Menopause Journal, October 2024. PMC, Estrogen and Metabolism: Navigating Hormonal Transitions from Perimenopause to Postmenopause, July 2025. Simple Hormones, Menopause By The Numbers, December 2025. Midi Health, Testosterone for Menopause, March 2026. PMC, Using Estrogen and Progesterone to Treat Menopausal Depression, 2025. NBC News, Doctors Looking Into Estrogen Therapy to Prevent Dementia in Women, November 2025. PMC, Testosterone and Pre-Androgens by Age and Menopausal Stage at Midlife, October 2025.