Why Do Hot Flashes Occur?

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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.

Hot and Cold

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Many women who are in their early 40’s and beyond experience a roller coaster ride with their internal thermostats which is absolutely maddening. They can go from sitting comfortably one minute, to a sudden sweat and flush which makes them feel like they are standing next to a fiery blaze the next minute. Such a roast-fest can last from seconds to minutes, after which a woman may feel pretty comfortable. But the pendulum can swing the other way, and the woman may suddenly feel very cold once the air conditioning has kicked in, prompting her to put on a sweater. Guess what? Chances are that sweater will be peeled off in a matter of minutes when the woman has another hot flash. Hot, cold, hot, cold, hot, cold. Fun times. Such fluctuations in a woman’s perception of temperature, coupled with her constant putting on and taking off layers of clothing, are often perceived as pretty nutty by people who don’t have a clue about the torture these women go through.

I can relate to the constant temperature fluctuations because I have been suffering from it for over a year now. I fully realize that my body doesn’t know what temperature it is. Thanks to hormonal imbalance and the decline associated with peri-menopause, I am very familiar with the sweating which is sudden and intense, and I know that feeling of desperation which has me peeling off clothes, fanning myself, and sticking my head in freezers and in front of blowing fans. However, I only recently began experiencing the feeling that I am suddenly freezing my butt off, and I truly can’t stand it. My perception of the ambient temperature can go from upper 70’s, to 120 degrees, to 60 degrees, within 5 minutes flat.

woman with chills

On my worst days I will have maybe five or six of these episodes, so the daytime hours aren’t too bad, but my evenings make up for the relative break I get during the day, because I am hot and sweaty for many hours and cannot cool down at all, even if I wear a cooling towel around my neck, lie on the floor under my ceiling fan (the darned thing is positioned right over the foot of the bed and doesn’t cool me off at all when I am in bed), and lie over the covers. My bedroom feels like it is 100 degrees and I cannot get away from the heat because, of course, the heat is emanating from ME. My hypothalamus is tricked every night into perceiving that my body needs to release excess heat. I know that this is the result of low estrogen levels, but my professional knowledge of estrogen therapy is enough to keep me from ever supplementing with estrogen, so I will continue to suffer as long as my hypothalamus triggers the way it does. At least I know I am not alone: about 85% of women who are peri-menopausal experience hot flashes. Hot flashes can last from several months up to 15 years, with an average of 2 years. I hope and pray that I fall into the average! Seriously, hot flashes and night sweats are absolutely miserable. I often get as little as two hours of sleep at night when my night sweats are in full effect!

Who Turned Up The Heat?

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If you have ever awakened in the middle of the night with the feeling that you are burning up, and find yourself drenched in sweat, you have experienced night sweats. Though night sweats can be aggravated by spicy foods or alcohol, or sleeping in an overheated room, the true culprit in night sweats for the majority of peri-menopausal and menopausal women is fluctuating estrogen levels. Such fluctuations falsely signal the hypothalamus to cool down the body by triggering perspiration and blood vessel dilation. For those of you who have experienced this phenomenon, you know how much it interferes with normal sleep patterns!

What can you do to minimize night sweats? Regular exercise can reduce the severity of symptoms. I have also seen a marked improvement in night sweat symptoms in my patients after they have introduced maca root into their daily regimens. On a personal note, maca has been helpful in reducing the intensity of my night sweats so that I don’t wake up completely drenched in sweat in the middle of the night. If you have severe symptoms, you might want to consider being evaluated for bio-identical hormone replacement therapy. I strongly advocate the use of bio-identical hormones for individuals who suffer from the symptoms of hormonal decline or imbalance.

The battle to eradicate my night sweats has not ended. I had a nice little break from them for about five months, then they crept back into my nightly patterns. To combat this, I decided that my comforter needed to be put in storage until the winter, and I purchased a cotton coverlet set. I also purchased a special mattress protector which is comprised of a cooling material, and though it was a bit pricey (about $100 for a Cal King), it was a godsend for me. Here are a couple of brands which are great:

http://www.amazon.com/Sleep-Better-Iso-Cool-11-ounce-Mattress/dp/B000ZK4QBY?tag=hotflashwebsite-20

http://www.amazon.com/Design-Weave-Outlast-Temperature-Mattress/dp/B003J371E8?tag=hotflashwebsite-20

Another thing I highly recommend is to put a fan in your bedroom. I have a ceiling fan in my bedroom, and I almost always sleep with it on so that I can keep cool air circulating over the bed. Make sure the thermostat in your home is set to a cooler temperature so that you don’t overheat during the night, or open a window to allow a cool night breeze drift into your bedroom.

Hopefully these suggestions will have you sleeping more comfortably this summer!