Hot Flashes During Perimenopause: Understanding and Coping with the Phenomenon

Hot flashes are the most characteristic symptom of perimenopause. They affect about 70 to 80 percent of women during the menopausal transition, but their frequency and intensity vary greatly from person to person. These sudden waves of heat result from a disruption in the brain’s “thermostat” in response to falling estrogen levels. They cannot be eliminated with a wave of a magic wand, but several strategies—such as temperature regulation, breathing techniques, mind-body approaches, targeted herbal medicine, and, if necessary, medical treatments—can significantly reduce their impact.

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What are hot flashes?

A hot flash (vasomotor flush) is a sudden and intense sensation of heat that spreads through the chest, neck, and face, often accompanied by flushing, a rapid heartbeat, and sweating, and sometimes followed by a chill. It is a cooling response triggered by mistake, even though the ambient temperature is not excessive. Episodes last from thirty seconds to a few minutes, occurring both during the day and at night (night sweats).

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Why do we experience hot flashes during perimenopause?

The erratic drop in estrogen disrupts the hypothalamus, the body's internal "thermostat."

• The thermostat goes haywire: the thermal comfort zone (the range within which we feel comfortable) narrows, and even the slightest variation triggers a disproportionate cooling response.
• Neurotransmitters come into play: a drop in estrogen affects serotonin and norepinephrine, which are involved in regulating body temperature and mood.
• The autonomic nervous system goes into overdrive: the sympathetic branch (the "stress" branch) becomes more responsive and promotes rapid vasodilation.

Recent research has provided a better understanding of this phenomenon. Specialized neurons in the hypothalamus, called KNDy neurons (kisspeptin–neurokinin B–dynorphin), play a central role in regulating body temperature. When estrogen levels decrease, these neurons become more active, further narrowing the thermal neutral zone and promoting the onset of hot flashes. This discovery explains, in particular, why new treatments targeting neurokinin B receptors may be effective in some women.

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💡 Why are hot flashes worse at night?

Body temperature naturally drops to help us fall asleep. The disrupted internal thermostat interprets this change as an abnormality and triggers sweating to “correct” the situation: this is what causes night sweats.

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How long do hot flashes last?

A seizure lasts from 30 seconds to a few minutes. The period during which they occur lasts an average of 7 years, but varies greatly from one woman to another; they may persist for longer.

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What You Can Do

Where to Start: Solutions for Immediate Comfort

• Thermal management (“layering technique”): several thin layers of natural fabrics (cotton, silk, linen, merino wool) to adapt instantly.
• Rhythmic breathing: Slow, deep breathing (about 6 breaths per minute) starting at the first signs of an attack calms the sympathetic nervous system; this is helpful even though its effect on the frequency of attacks remains modest.
• Identify your triggers: Keep a journal (using the Ainoha app) to identify coffee, alcohol, spicy foods, and stress; avoid very hot beverages.
• Saffron: approximately 30 mg/day: Available data suggest a primarily indirect benefit. Saffron mainly improves mood, anxiety, and sleep quality—three factors that may reduce the discomfort associated with hot flashes—rather than having a direct effect on the vasomotor symptoms themselves. The data are promising but show publication bias.

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💡Does coffee make hot flashes worse?

For people who are sensitive to it, yes: caffeine increases heart rate and may be enough to trigger an attack. A temporary elimination test can help you determine if this applies to you, rather than cutting it out entirely.

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Things to Explore

• CBT and hypnosis: Cognitive-behavioral therapies and hypnosis reduce the discomfort experienced and the perceived frequency of hot flashes by changing the way the brain processes the heat signal. This is the best-supported nonhormonal approach.
• Black cohosh (Cimicifuga): Unlike phytoestrogens, it has no clear estrogenic activity (it may even be antiproliferative in vitro), which explains why it is sometimes considered when phytoestrogens should be avoided. However, its effectiveness is debated (several trials, particularly in women who have had breast cancer, have shown no greater benefit than a placebo). Results remain inconsistent across studies, and several scientific societies believe the evidence is insufficient to recommend it routinely.

⚠️ Medical advice—and, in particular, oncological advice if you have a history of hormone-dependent cancer—is essential.

• Red clover: Rich in isoflavones (phytoestrogens), it shows modest and inconsistent efficacy in treating hot flashes (especially at high doses, ≥80 mg/day of isoflavones). The best results appear to be observed with certain standardized preparations rich in biochanin A, but the benefits remain modest.

⚠️ Contraindicated in cases of hormone-dependent cancer; use with caution in patients receiving anticoagulant therapy (coumarins).

• Acupuncture: may improve quality of life and reduce the frequency of hot flashes, with results varying across studies.
• Magnesium, vitamin E: Evidence of a direct effect on hot flashes remains limited. However, in women experiencing significant stress or a documented deficiency, magnesium may help improve sleep and reduce nervousness, which can indirectly make the symptoms more bearable.

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💡 Is soy effective against hot flashes?

Soy isoflavones modestly reduce the frequency and severity of hot flashes, but the effect depends on several factors, not just the well-known ability of the microbiota to produce equol. Other factors include the dose and genistein content, the form (whole food or supplement), the duration of use (several weeks), and the initial severity; in fact, some trials conducted in women who are “equol producers” show no effect at all.

Equol (produced by only 30 to 50 percent of people) has the strongest effect, but it does not explain everything.

In terms of safety, soy consumed as food (tofu, tempeh, miso, edamame, natto, etc.) is considered safe as part of a balanced diet, including for most postmenopausal women. Fermented foods, such as miso, tempeh, and natto, also offer significant nutritional benefits. However, isoflavone-concentrated supplements are still not recommended for those with a history of hormone-dependent cancer, unless otherwise advised by a healthcare professional.

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Week by Week: Long-Term Prevention

• Room temperature: Maintain a temperature of 16 to 18 °C; consider using a cooling mattress pad or a quiet fan to reduce night sweats. (clinical judgment)
• Avoid identified triggers: based on your diary (coffee, alcohol, spicy foods), without following any unnecessary restrictive diets. (clinical common sense)
• Maintaining a healthy weight: Several studies show that being overweight—particularly having excess abdominal fat—is associated with more frequent and intense hot flashes. Gradual weight loss, when appropriate, can help reduce symptoms.
• Exercise regularly: Physical activity alone won’t make hot flashes go away, but it improves sleep quality, mood, energy levels, and quality of life. These benefits often make it easier to cope with the menopausal transition.
• Reducing chronic stress: A constantly activated sympathetic nervous system can amplify the perception of hot flashes. Approaches such as breathing exercises, cardiac coherence, yoga, or mind-body therapies can help reduce this reactivity.
• Quitting smoking: Smoking is associated with an earlier onset of menopause and more frequent and severe hot flashes. Quitting smoking offers benefits that go far beyond relief from vasomotor symptoms.

In general, diet, sleep, and physical activity affect many symptoms throughout your perimenopause.

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When should you talk to a professional about it?

It is recommended that you seek medical advice if hot flashes are significantly affecting your quality of life or sleep, if they are accompanied by unusual heart palpitations or shortness of breath, or if you are experiencing signs of severe fatigue or depression.

You can then discuss medical options: hormone therapy for menopause (currently the most effective scientifically validated treatment for hot flashes, when indicated and provided there are no contraindications), or non-hormonal alternatives—certain low-dose antidepressants (venlafaxine, paroxetine—taking interactions into account), and neurokinin-3 receptor antagonists (fezolinentan and the more recent elinzanetant), which are effective against hot flashes but require certain precautions (for example, liver function monitoring for fezolinentan, which is not combined with HRT).

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Take It Further with Ainoha

• Trigger Journal and Périscore: Recording episodes and their triggers helps you gain an objective perspective on what affects you and measure the impact of changes.

💡 Note: “Natural” does not mean “without precautions.” Phytoestrogens (red clover, high doses of soy) are specifically not recommended for people with a history of hormone-dependent cancer. Before incorporating a herbal remedy or supplement into your regular routine, consult your doctor or pharmacist.

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Symptoms Often Associated With This Condition

• Night sweats: and the resulting sleep disturbances.
• Sensitivity to cold and cold extremities: the thermal "roller coaster" effect.
• Heart palpitations and dizziness: caused by fluctuations in blood pressure during hot flashes.
• Irritability and fatigue: often made worse by a lack of sleep.