The Most Common Symptoms
of Perimenopause — and Why
They're Often Overlooked

You sleep — and are still tired. You train — and recover worse than before. You function — but no longer feel quite like yourself. Many women describe exactly this phase as difficult to grasp. Not dramatic enough to seem "ill". But clear enough to feel: something has changed.

Perhaps you're noticing:

• More inner restlessness
• Poorer sleep
• Hot flashes or night sweats
• Brain fog
• Word-finding difficulties
• More belly fat
• Stronger exhaustion
• Less resilience
• Cravings or energy crashes
• Irritability or mood swings

Because many of these changes are biologically understandable — particularly in the phase of life from the mid-30s to mid-40s. Not every woman is automatically in perimenopause. But for many, this is when the first hormonal, neurological, and metabolic changes begin, which can influence sleep, energy, mood, and recovery.

The Silent Transition Phase That's Rarely Discussed

Perimenopause doesn't simply mean "no more periods". The hormonal changes often begin many years beforehand. And this is precisely why many women barely recognise themselves in this phase. How that span breaks down, and how long perimenopause actually lasts, I have covered separately.

Particularly typical: cycle changes, poor sleep, brain fog, altered body composition, stronger stress responses, and emotional sensitivity. The difficult part: the symptoms often seem unremarkable individually. Together, however, they form a clear pattern.

Many women then hear things like: "That's just stress." or "You're getting older." Yet modern research now shows very clearly: hormones, the nervous system, sleep, and metabolism influence each other far more strongly than was long assumed.

Why Your Body Suddenly Responds Differently

Between 35 and 45, several systems often change simultaneously. Not abruptly. Rather quietly. And this is precisely why this phase is frequently overlooked.

1. Progesterone begins to slowly decline

Progesterone has a calming effect on the nervous system. As it slowly drops, many women report inner restlessness, poorer sleep onset, more sensitive stress responses, and stronger emotional irritability — often long before the cycle becomes irregular.

2. Estrogen fluctuates more strongly

Estrogen influences, among other things, serotonin, dopamine, sleep, concentration, skin, libido, and mood. During perimenopause, estrogen doesn't simply decline linearly — it often fluctuates more strongly and unpredictably. And these fluctuations feel for many women like an inner rollercoaster.

3. The nervous system loses its stress buffer

Many women function for years in a constant stress mode: work, family, mental load, responsibility, too little genuine recovery. At some point, the nervous system responds more sensitively. Joel Jamieson describes this state as chronic overactivation of the sympathetic nervous system — the "accelerator mode" of the autonomic nervous system. The result: poorer recovery, heightened stress perception, poor sleep, and stronger exhaustion despite functioning.

The Most Common Symptoms — Biologically Explained

Fatigue Despite Sleep

Many women sleep a sufficient number of hours — but no longer with sufficient depth. Particularly common: waking at night, light sleep, early waking, the feeling of "tired but awake". Low progesterone, heightened evening tension, and cortisol can significantly affect sleep quality.

Brain Fog & Concentration Problems

Word-finding difficulties. Forgetfulness. Mental fatigue. The so-called "brain fog" is one of the most common complaints of this phase of life. These symptoms are often connected to sleep deprivation, hormonal fluctuations, stress load, and emotional exhaustion. Research shows that these changes are real — even though many women have long felt they weren't being taken seriously.

More Belly Fat Despite the Same Lifestyle

Many women say: "I'm not really doing anything fundamentally different." And yet the body changes. Particularly typical: more fat in the abdominal area, less muscle definition, poorer insulin sensitivity, and stronger water retention. Chronically elevated cortisol can promote visceral fat deposits. At the same time, with less muscle mass, metabolic flexibility often decreases.

Poorer Recovery After Exercise

What used to give energy suddenly feels exhausting. Too much HIIT, chronic cardio, or sleep deprivation combined with hard training can additionally stress the nervous system. This is why strength training gains enormous importance in this phase of life — not as calorie burning, but as protection for muscle mass, metabolism, bone health, hormonal balance, and the nervous system.

The Invisible Factor: Allostatic Load

The term "allostatic load" from stress research describes this cumulative burden on the body. The body remains permanently on alert — and this changes cortisol, sleep, HRV, blood sugar, inflammatory processes, mood, and recovery. Bruce McEwen, one of the most important stress researchers, described allostatic load as the "price" the body pays for chronic adaptive stress.

What Your Body Really Needs Now

The good news: the body is adaptable. Many women don't need more hardness — but more precision.

• Prioritise sleep Sleep influences hormones, hunger, cortisol, recovery, mood, and muscle building. Helpful: regular sleep times, less alcohol in the evening, a cool bedroom, less screen light, and morning light directly after waking.
• Morning light instead of immediately reaching for your phone Even 5–10 minutes of natural light after waking can help rhythmically regulate cortisol, stabilise energy, and improve sleep pressure in the evening.
• Strength training instead of constant cardio 2–3 strength sessions per week with a focus on compound exercises, moderate intensity, and adequate recovery. Not maximum exhaustion — but getting systematically stronger.
• Consciously integrate protein A more consistent protein intake can help during hormonal transition phases with muscle mass preservation, satiety, blood sugar, energy, and recovery.
• Actively calm the nervous system Slow exhalation, breathing exercises, walks, NSDR/Yoga Nidra, short conscious breaks. The goal: regularly signalling safety to the body.

When You Should Look More Closely

Not every symptom after 35 is automatically hormonal. This is why good diagnostics are important. Worth having checked: iron/ferritin, thyroid, vitamin B12, vitamin D, blood sugar, as well as heavy bleeding, persistent exhaustion, and pronounced mood symptoms.

Many complaints overlap. And this is precisely why this phase of life needs less self-criticism — and more understanding for one's own body.