The heat rises in you like summer lightning—sudden, fierce, and then gone, leaving you flushed and wondering if anyone noticed.
About 75% of us experience this.Freeman EW, Sherif K. Prevalence of Hot Flushes and Night Sweats Around the World: A Systematic Review. Climacteric. 2007;10(3):197-214. The median duration is 7 yearsAvis NE, et al. Duration of Menopausal Vasomotor Symptoms Over the Menopause Transition. JAMA Internal Medicine. 2015;175(4):531-539.—though for some women, it's much longer. This isn't a minor inconvenience. It disrupts sleep (over 90% of women report this), concentration, mood, energy, and yes, sexual function.Brown JN, et al. Association of Menopausal Vasomotor Symptom Severity with Sleep and Work Impairments: A US Survey. Menopause. 2023;30(9):897-904.It’s real. It’s physiological. And we finally understand why it happens.
What’s Actually Happening
Deep in your brain, in a region called the hypothalamus, there’s a thermostat. Normally, it tolerates a range of temperatures—about 0.4°C—before deciding you’re too hot or too cold.
During perimenopause, that range shrinks to nearly nothing.
Why? Because of neurons called KNDy neurons that sit right next to your thermostat.Rance NE, et al. Modulation of Body Temperature and LH Secretion by Hypothalamic KNDy (Kisspeptin, Neurokinin B and Dynorphin) Neurons. Frontiers in Neuroendocrinology. 2013;34(3):211-227. When estrogen is stable, these neurons stay calm. When estrogen drops—or fluctuates wildly—they become hyperactive. They flood your temperature control center with signals, narrowing your comfort zone until the slightest shift triggers a full heat-dissipation response.
Your blood vessels dilate. Your skin flushes. You sweat. Your body is desperately trying to cool down from heat that doesn’t actually exist.
That’s a hot flash. It’s not in your head. It’s in your hypothalamus.
Why Some Women Have It Worse
Individual variation is real:
- Genetics matter: Your sensitivity to estrogen changes, the density of receptors in those neurons—these vary
- Body composition plays a role: Higher body fat can mean more severe symptoms (adipose tissue produces some estrogen but also insulates)
- Race and ethnicity affect patterns: Research shows different prevalence and duration across groups
- Triggers are individual: What sets off a flash for one woman may not affect another
Common Triggers
Many women notice patterns:
- Alcohol
- Spicy foods
- Caffeine
- Stress
- Warm environments
- Hot beverages
Tracking your own triggers can help—not to eliminate the flashes entirely, but to have some sense of agency in when they happen.
The Night Sweat Problem
When hot flashes happen at night, they’re called night sweats—and they’re the reason so many of us wake drenched, throwing off blankets, then freezing. Sleep disruption from night sweats cascades into everything else: mood, cognition, energy, patience.
This is why treating hot flashes isn’t vanity. It’s about being able to function.
What Actually Helps
I won’t go into full detail here—that’s in Support Options—but briefly:
Hormone therapy remains the most effective treatment for hot flashes. Estrogen directly addresses the underlying mechanism.
NK3 receptor antagonists (like fezolinetant) are a newer option that blocks the hyperactive neurons directly, without estrogen. This is proof that the mechanism is real and targetable. More on this in Beyond Hormones.
Lifestyle modifications can help at the margins—layered clothing, keeping the bedroom cool, avoiding triggers, managing stress.
Some antidepressants (SSRIs, SNRIs) have modest effects on hot flashes, though the mechanism isn’t fully understood.
I know this symptom can feel embarrassing, trivializing, almost comic—the menopausal woman fanning herself has become a cliché. But there’s nothing trivial about living in a body whose thermostat has gone haywire.
This is real. And there are real options for support.