For any of you ladies who have experienced hot flashes, you know how sudden and intense they can be. It’s as if a radiator suddenly turns on in your head, neck or chest, making you miserable. But why do perimenopausal and menopausal women get these things?
Hot flashes are related to fluctuating hormones that happen before, during and after menopause. Research suggests that dropping estrogen can change how the brain perceives temperature. In other words, our internal thermostat (hypothalamus) doesn’t work properly, so when it starts to think your body is too hot, it opens up all the blood vessels on the skin and the sweat glands to cool it off.
Here’s a breakdown of the physiology behind hot flashes:
1. Estrogen Decline and Hypothalamic Dysfunction
Estrogen plays a crucial role in regulating body temperature by influencing the hypothalamus, the brain’s temperature control center. During perimenopause and postmenopause, estrogen levels fluctuate and eventually decline, disrupting normal hypothalamic function.
2. Narrowed Thermoregulatory Zone
The hypothalamus maintains a “thermoneutral zone,” a temperature range in which the body does not need to trigger heat loss (sweating) or heat retention (shivering). In menopausal women, lower estrogen levels lead to a narrowing of this zone, meaning even small changes in core body temperature can trigger an exaggerated heat dissipation response.
3. Activation of the Sympathetic Nervous System
Due to the narrowed thermoregulatory zone, a slight increase in body temperature (which would be tolerated normally) is misinterpreted as excessive heat. This causes the hypothalamus to activate the sympathetic nervous system, leading to:
- Vasodilation: Blood vessels, especially in the skin of the face, neck, and chest, dilate rapidly to release heat, causing a flushed appearance.
- Increased Heart Rate: The heart pumps faster as part of the body’s attempt to cool down.
- Sweating: The body triggers sweat production to dissipate heat through evaporative cooling.
4. Sudden Cooling and Chills
After the hot flash, the body may overcorrect, leading to a rapid decrease in temperature, causing chills or a cold sensation.
There are measures which a woman can take to minimize the chances of getting hot flashes. They include avoiding hot weather, spicy foods, caffeine, alcohol, and stress. But hot flashes can even strike in very cold weather, because the low estrogen levels can make a woman’s thermoregulatory apparatus go haywire. What has worked exceptionally well for me in the past has been the use of table fans on both nightstands in my bedroom and a ceiling fan overhead. Sleeping with a cold gel pack between the shoulder blades is also very effective.
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