The Heat Nobody Explained: The Science Behind Hot Flashes

It rises from your chest, up to your face, your heart speeds up a little and, seconds later, the sweat arrives. If this sounds familiar, you're not strange and you're not exaggerating: it's the most common symptom of the menopause transition, and it happens to up to 80% of women.

What really happens in the brain

For years it was explained in a very simplified way: "oestrogen drops, so you feel hot". Today's science goes further. In the hypothalamus, which acts as the body's thermostat, there are neurons called KNDy neurons which, when oestrogen falls, become overactive and completely disrupt the perception of body temperature. The brain thinks it's too hot, even when it isn't, and triggers an emergency cooling response: blood vessels dilate, you sweat, your pulse speeds up.

This finding isn't just scientific curiosity: it has been the basis for developing completely new medicines that act directly on those neurons, instead of replacing hormones. We'll talk about them later on.

What the evidence says

• Hot flashes affect 70-80% of women in the menopause transition; around 25% experience them as moderate or severe.
• The median duration after the last period is around 4.5 years (and the total duration about 7 years), although for some women they last considerably longer.
• Stress, obesity, smoking, poor sleep and anxiety in perimenopause are associated with more intense and persistent hot flashes.

Why are some women hit much harder?

There's no single explanation. Genetic factors, body mass index, smoking and also psychosocial factors such as chronic stress all play a part. This explains why two women with the same hormonal profile can experience this stage completely differently, and why there's no single solution that works for everyone.

What you can do now

• Identify your own triggers: hot environments, alcohol, caffeine, heavy meals.
• Dress in layers that are easy to take off.
• Prioritise rest: lack of sleep makes hot flashes worse, and hot flashes make sleep worse. It's a cycle worth breaking as soon as possible.
• If they interfere with your daily life, it's not something you "just have to put up with": effective treatments exist, and we'll cover all of them in this series.

Dr. Alma García, Vive Tu Balance

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