Freezing, then drenched, then freezing again

Heat and cold tolerance

5 min read

The room is the same temperature it was yesterday. Yesterday it was fine. Today you are peeling off a layer, flushed and damp, and ten minutes later pulling it back on because you are cold again. Your body has a comfort band between the point where it starts sweating and the point where it starts shivering. In midlife, that band can narrow until it is almost gone.

You are not overheating because you are anxious. You are not cold because something is wrong with you. Your thermoregulatory system is responding to a real change in its operating conditions, and what you feel is a direct consequence of that change.

Your core body temperature sits within a range where neither sweating nor shivering is triggered. This range is called the thermoneutral zone. In a landmark study, Freedman and Krell measured it in symptomatic and asymptomatic postmenopausal women. In the symptomatic group, the zone was 0.0 degrees Celsius. In the asymptomatic group, it was 0.4 degrees. The difference was statistically significant (P < .005). A temperature fluctuation too small to register on a household thermometer was enough to cross a threshold and trigger a full heat-dissipation response.

The mechanism involves a group of hypothalamic neurons that co-express kisspeptin, neurokinin B, and dynorphin, known collectively as KNDy neurons. These neurons regulate both reproductive signaling and thermoregulation. When estrogen declines, they lose an inhibitory input and become hyperactive. This hyperactivity narrows the thermoneutral zone and lowers the threshold at which the body initiates sweating and vasodilation. Neurokinin B signaling from these neurons to the preoptic area of the hypothalamus is the pathway that a new class of medications, the NK3 receptor antagonists, was designed to block.

Vasomotor symptoms affect up to 80 percent of menopausal women. The mean duration is seven to ten years, and for roughly a third of women it persists longer than ten. The NAMS 2023 position statement identifies these as the most common symptoms of menopause and notes that they are undertreated.

What it does not establish

The KNDy neuron model is supported by animal studies and human neuroimaging but has not been directly measured in living human hypothalamic tissue. Estrogen levels do not differ between symptomatic and asymptomatic postmenopausal women, which means estrogen depletion alone does not explain who gets hot flashes and who does not. Elevated central sympathetic activation is another factor that narrows the zone. These studies describe the population-level mechanism. They cannot predict the severity, timing, or duration of vasomotor symptoms in any individual woman.

The thermoneutral zone

Core body temperature is normally regulated between an upper threshold for sweating and a lower threshold for shivering. Between those thresholds, the body makes small adjustments through changes in peripheral blood flow. When the zone narrows, those small adjustments are no longer enough. A tiny rise in core temperature crosses the sweating threshold and the body responds with everything it has: vasodilation, sweating, flushing. Then it overshoots and you feel cold.

The numbers

0.0°C vs 0.4°C

Thermoneutral zone width in symptomatic versus asymptomatic postmenopausal women (Freedman and Krell, American Journal of Obstetrics and Gynecology, 1999). The symptomatic women had virtually no buffer between sweating and shivering.

Up to 80%

Prevalence of vasomotor symptoms in menopausal women, with a mean duration of 7 to 10 years (NAMS 2023 Nonhormone Therapy Position Statement)

A thermoneutral zone of zero means any change in core temperature triggers a response. The body is not malfunctioning. It is doing exactly what it is supposed to do with a drastically narrowed operating range. The freezing-then-drenched cycle is the physiology working as designed, just within constraints that were not there before.

Fatal heart attack at 71.

Her father took statins for 9 years.

Every visit he told his doctor the muscle pain was getting worse.

Every visit the doctor said: "That's normal."

He died of a heart attack at 71.

Cholesterol… Perfect.

Drug… Worked exactly as designed.

But he died anyway.

His daughter is a heart health researcher. That funeral was the day she started asking the questions her industry didn't want her to ask.

What she found has a name.

Almost no doctor screens for it. Almost no patient has heard of it.

She finally said it on camera:

If your parents took statins, or you do, or someone you love does…

Please watch this in the next 20 minutes before it’s taken down

P.S. Watch her face when she gets to the part about her father. She's not a person who shows emotion. It still gets her → Almost no doctor screens for this

The intervention with the strongest evidence

Cognitive behavioral therapy for vasomotor symptoms

Recommended (NAMS 2023)

The NAMS 2023 Nonhormone Therapy Position Statement recommends CBT for vasomotor symptoms based on Level I evidence. CBT has been shown to reduce the degree to which hot flashes are rated as a problem. It does not reduce their frequency. It changes the distress and disruption they cause. This distinction matters: the episodes continue, but their impact on daily life and sleep is measurably reduced. Hormone therapy remains the most effective treatment for VMS and should be considered for symptomatic women within ten years of their final menstrual period.

“Hormone therapy remains the most effective treatment for vasomotor symptoms and should be considered in menopausal women within 10 years of their final menstrual periods.”

NAMS 2023 Nonhormone Therapy Position Statement

What it is not

NAMS does not recommend cooling techniques, paced respiration, supplements, or herbal remedies as treatments for vasomotor symptoms. ACOG endorses common-sense environmental adjustments such as layering and lowering ambient temperature as comfort measures. These are practical, not curative. The steps below fall in that category.

When to call

If vasomotor symptoms are affecting your sleep, your ability to work, or your quality of life, the ACOG 2026 guideline recommends discussing treatment options with a provider. These are treatable symptoms with multiple evidence-based options.

Night sweats accompanied by unexplained weight loss, fever, or lymph node swelling. These patterns may indicate something other than vasomotor symptoms and need separate evaluation.

This week

Lower your bedroom temperature tonight. If your thermoneutral zone is narrow, sleeping in a warm room almost guarantees a night sweat. Try 65 to 67 degrees Fahrenheit (18 to 19 Celsius). This is a comfort measure endorsed by ACOG, not a proven treatment for VMS frequency.

Dress in layers you can open or remove in under five seconds. The thermoneutral zone science explains why: when the zone is narrow, the body overshoots in both directions. Being able to adjust quickly limits the time spent on either side of the threshold.

If the episodes are frequent enough to disrupt your day or your sleep, write down how many you notice this week and bring the count to a provider. Vasomotor symptoms are the most common reason women seek menopause care, and the treatment landscape has changed in the last two years.

The freezing-then-drenched cycle is not fragility. It is the physics of a body operating with a thermoneutral zone that barely exists. You did not create it by being stressed, by drinking coffee, or by not being tough enough. It is a measurable change, it has a mechanism, and there are things that can be done about it.

One tap, no form

Which part of the cycle is worst for you?

Tapping opens a prepared reply. Nothing is public. What most readers tap decides what gets explained next.

The sudden heat that comes out of nowhere

The cold that follows and will not lift

The night sweats that wake me up soaked

None of these, but something changed

Or write in your own words. Every reply is read.

Read recent issues

Every source read for this issue

One thermoregulation study, one comprehensive review, one mechanistic hypothesis paper, one clinical position statement, and one clinical practice guideline.

1	Reduced thermoregulatory null zone in postmenopausal women with hot flashes Freedman and Krell, Am J Obstet Gynecol, 1999

2	Menopausal hot flashes: mechanisms, endocrinology, treatment Freedman, J Steroid Biochem Mol Biol, 2014

3	Modulation of body temperature and LH secretion by hypothalamic KNDy neurons Rance et al., Front Neuroendocrinol, 2013

4	The 2023 Nonhormone Therapy Position Statement NAMS, Menopause, 2023

5	Management of Menopause-Related Vasomotor, Sleep, and Mood Symptoms ACOG Clinical Practice Guideline, Obstet Gynecol, 2026

Fatal heart attack at 71.

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