Fatigue in perimenopause: it is not always “hormonal”

You are exhausted. Not tired from a bad night: exhausted in a way that does not yield to rest. You are 46, 48, 51, and the answer comes almost every time: "it's hormonal, it will pass".

That answer has a cost. Because behind fatigue in your forties lie common causes, easy to look for and often treatable, some of them directly linked to what is happening in perimenopause. This article gives you what you need to arrive at your appointment with the right questions.

« It is not just menopause »

That is literally the title of a study published from the American SWAN cohort, which followed 3,289 women for sixteen years^[2]. The researchers identified six symptom profiles in it, from highly symptomatic to asymptomatic.

Two results are worth knowing. First, a quarter of women were already highly or moderately symptomatic in pre-menopause, so before the transition. Second, these profiles were largely stable: depending on the group, 39 to 76% of women stayed in the same category over the years.

Fatigue, sleep problems and hot flashes often go together, that is true. But attributing all fatigue to menopause would be a mistake: for many women, it was already there. That does not mean menopause has nothing to do with it; it means it is not the only explanation, and that you have to look further.

The link nobody makes: heavy periods

Perimenopause often comes with heavier or longer periods. We know it, we treat it as ordinary. An analysis of the SWAN cohort published in 2025, covering 2,329 participants followed with daily menstrual calendars over seven annual visits, is an invitation to stop doing so^[1].

Women reporting at least three episodes of heavy bleeding over six months had a significantly higher risk of reporting fatigue (odds ratio 1.62; 95% confidence interval: 1.11 to 2.38). And this link persisted after adjustment for ethnicity, age, BMI, use of hormone therapy, depressive and anxiety symptoms, perceived stress, sleep problems and smoking.

One point of honesty: this study measured neither ferritin nor haemoglobin. It therefore does not demonstrate that the mechanism is iron deficiency; that is a plausible hypothesis, not a conclusion. But it gives a very concrete reason to report heavy periods to your doctor rather than treating them as the price to pay.

Iron: to look for, never to take blindly

It is the most frequently missed differential diagnosis, and there is a subtlety: you can be short of iron without being anemic. The blood count can be normal while stores, measured by ferritin, are low.

A meta-analysis brought together six randomized trials on this precise point: in fatigued people with iron deficiency without anemia, iron supplementation reduced fatigue, with an effect size of 0.33 (95% confidence interval: 0.17 to 0.48)^[3]. A real effect, then, but a modest one. Note that the cross-sectional studies included in the same publication did not find a significant association: the subject remains debated, and the authors call for clearer criteria to identify who benefits from supplementation.

What must absolutely not be concluded from it: "I am tired, I am going to take iron". Iron is never taken blindly. Testing (ferritin, blood count) is essential beforehand, because iron overload is not harmless.

The thyroid: the nuance that changes everything

Hypothyroidism shares many symptoms with menopause, and it must be looked for. But two very different situations have to be told apart.

Overt hypothyroidism is treated, and treatment improves symptoms.

Subclinical hypothyroidism (slightly raised TSH, normal thyroid hormones) is another matter. A meta-analysis of 21 randomized trials covering 2,192 adults showed that thyroid hormone therapy improved neither general quality of life nor thyroid symptoms, even though it did normalize TSH^[4]. The level of evidence is judged moderate to high here, and the authors conclude that these results do not support the routine use of thyroid hormone therapy in this situation.

What that means in practice: measuring TSH in the face of fatigue makes sense. Prescribing levothyroxine by reflex for a borderline TSH, much less so.

Sleep apnea: the diagnosis nobody looks for in women

The classic picture (a man, a snorer, overweight) causes many women to be missed. Two large American cohorts (Nurses' Health Study I and II), totalling more than 100,000 women, shed useful light^[5].

Surgical menopause was associated with a risk of obstructive sleep apnea about 27% higher than that of natural menopause (pooled hazard ratio 1.27; 95% confidence interval: 1.17 to 1.38). Notably: the excess risk was more marked in women who were not obese and in those who had never used hormone therapy.

An important reservation: this study measures the link between menopause and apnea, not the link between apnea and fatigue. And apnea remains a minority among the causes of fatigue. But if your fatigue comes with unrefreshing sleep, snoring, breathing pauses noticed by those around you, daytime sleepiness or headaches on waking, it deserves to be raised.

What really works

The best available evidence does not concern a medication. A randomized trial from the MsFLASH network tested cognitive behavioural therapy for insomnia in 106 women aged 40 to 65 with moderate insomnia and daily hot flashes. It was delivered by telephone, not even in person^[6].

At eight weeks, the insomnia severity score had fallen by 9.9 points in the treated group, versus 4.7 points in the group receiving menopause education. Above all: 70% of women in the CBT-I group had come out of insomnia, versus 24% of the control group. A revealing detail: the frequency of hot flashes did not budge, but the bother they caused decreased, and this benefit still held six months later.

A pooled analysis of individual data from 1,005 women drawn from four randomized trials completes the picture^[7]. Seven approaches were compared in it. On hot flashes, estradiol clearly dominates. But on the physical dimension of quality of life (the one that covers energy), it is cognitive behavioural therapy for insomnia and exercise that give the best results. Note: omega-3 did not appear among the effective interventions on any dimension.

On exercise, let us be precise. A systematic review shows a benefit on the physical and psychological quality of life of symptomatic women^[9]. But another meta-analysis, covering 21 trials and 2,884 participants, is categorical: exercise does not reduce the frequency of hot flashes, and that is established with a good level of certainty^[10]. Exercising remains highly recommendable for energy, mood, sleep, bones and heart; simply, not by promising the end of hot flashes.

What does not work, and the most stubborn myth

You will surely come across the term "adrenal fatigue", often accompanied by a salivary cortisol test to do at home and a range of supplements to buy. It has to be said clearly: this entity is recognized by no learned endocrinology society.

A systematic review examined 3,470 papers and retained 58 studies^[8]. The results of the tests studied are contradictory almost systematically, whatever their quality and validation. The authors conclude bluntly that adrenal fatigue remains a myth.

Beware of a confusion that would be dangerous: adrenal insufficiency is a real, serious and well documented disease. That is not what is at issue here, but the commercial concept of "adrenal fatigue".

That obviously does not mean your fatigue is imaginary. It means that this particular diagnosis does not explain it, and that going after it often amounts to missing real and treatable causes.

As for "energy" supplements, adaptogens and detox cures: none of the sources examined for this article establishes their effectiveness on the fatigue of perimenopause. We will not claim they are ineffective; we note that there is no evidence of effectiveness, which is not the same thing, and which is enough to advise investing elsewhere.

When to see a doctor, and with what

To raise at a scheduled appointment: fatigue that lasts several weeks and does not yield to rest; periods that have become heavy or prolonged; unrefreshing sleep, snoring or daytime sleepiness; persistent sadness, loss of interest or unusual irritability (depression is a cause of fatigue in its own right, and it is treatable); unusual thirst or frequent urination; a vegetarian or vegan diet, bariatric surgery, or prolonged treatment with a proton pump inhibitor or metformin (situations at risk of vitamin B12 deficiency).

The first-line workup is discussed with a doctor. It often includes a complete blood count, a ferritin, a TSH and a blood glucose, and depending on the context a vitamin B12 and a vitamin D. This workup is prescribed and interpreted: neither online self-tests nor salivary cortisol measurements sold without prescription replace it.

Prompt advice is justified in case of very heavy bleeding (protection to be changed every hour for several hours), large clots, or bleeding accompanied by breathlessness, dizziness, palpitations or pallor. Also: any bleeding occurring after twelve months without periods must be investigated, without delay and without panic. And of course, unusual breathlessness, chest pain or feeling faint.

Frequently asked questions

My fatigue at 48, is it necessarily menopause?

No. In the SWAN cohort, which followed nearly 3,300 women for sixteen years, a quarter of them were already highly or moderately symptomatic even before pre-menopause, and these profiles were largely stable over time. Menopause plays a part, but it does not explain everything. Several common and treatable causes deserve to be looked for: iron deficiency, thyroid disorders, sleep apnea, depression, diabetes, vitamin B12 or D deficiency.

I am tired, should I take iron?

Not without testing. You can be short of iron without being anemic, and a meta-analysis of randomized trials shows that supplementation then reduces fatigue, with a real but modest effect. But iron is never taken blindly: iron overload is not harmless. A ferritin measurement and a blood count are essential beforehand, and supplementation is prescribed.

My TSH is slightly raised: should it be treated?

Not automatically. A meta-analysis of 21 randomized trials covering 2,192 adults showed that thyroid hormone therapy in subclinical hypothyroidism (raised TSH but normal thyroid hormones) improved neither quality of life nor symptoms, even though it normalized TSH. The level of evidence is judged moderate to high. This does not concern overt hypothyroidism, which is treated. The decision rests with your doctor.

Does "adrenal fatigue" exist?

It is recognized by no learned endocrinology society. A systematic review that examined 3,470 papers and retained 58 studies concludes that the results are contradictory almost systematically and that this is a myth. Be careful not to confuse it with adrenal insufficiency, which is a real and serious disease. That this particular diagnosis does not exist obviously does not mean your fatigue is imaginary: it means the right cause has to be looked for.

Will exercise make my hot flashes and my fatigue disappear?

On hot flashes, no: a meta-analysis of 21 trials and 2,884 participants establishes with a good level of certainty that exercise does not reduce their frequency. On energy and physical quality of life, on the other hand, exercise comes out favourably, and it appears with cognitive behavioural therapy for insomnia among the most effective approaches on that dimension in a pooled analysis of four randomized trials. Exercising therefore remains highly recommendable, but not for hot flashes.

⚠️ This article is provided for informational and educational purposes only. It does not replace medical advice, diagnosis or treatment. Always consult your doctor or a qualified health professional with any questions about your health.

How we work: our editorial method · Written and verified by Bouchra, editorial lead.

How we work: our editorial method · Written and verified by Bouchra, editorial lead.