Blog of the Society for Menstrual Cycle Research

Hot Flashes Are Weird

November 12th, 2012 by Paula Derry

I have two pretty contradictory sets of opinions about hot flashes. In a previous blog post, I emphasized one of them. Namely, that flashes are a mind/body phenomenon in which a woman’s interpretation of her physical experiences are central to her being distressed or not, of being able to cope or not, of what an experience is and means. A woman can identify her “real” self with her thoughts or her body, or she can experience her embodied self as a totality. In my first set of attitudes, the diversity of physical experiences is part of the mix: The same term, “hot flash,” is used for a wide family of experiences that range from mild to unbearable, from heat to heart palpitations, from empowerment to anxiety. However, in my second set of opinions, physical experience is front and central, and my thoughts can be summarized as follows: Hot flashes are weird.

In a conventional view, flashes are simply something that happens because of the hormonal changes surrounding menopause. They are often defined as a transient feeling of heat, sometimes accompanied by sweating or the skin turning red, that typically lasts a few minutes but can persist up to an hour. Flashes are most common in the years surrounding menopause but can begin many years before or occur many years after the final menstrual period. One theory is that fluctuating levels of estrogen affect a part of the brain that controls heat regulation. As a result, small changes in temperature are interpreted by the brain as meaning that the body’s temperature is outside the normal range; the hot flash is the body’s attempt to cool the body down. Alternatively, perhaps the hormonal imbalance affects the brain or other endocrine glands in other ways, or perhaps some women are simply more sensitive to these changes.

However, the experience of flashes is complex. A woman who is overheated for other reasons may not feel like a woman having a hot flash. A flashing woman might feel like she is on fire. Or she may feel hot only in an isolated body part, like her back or earlobes. Or the feeling of heat may start in one part of the body (like her head or upper back) and travel. Some women may not realize their feeling of gentle warmth is caused by a flash until later. Further, there are experiences in addition to that of warmth. The experience might feel like anxiety rather than heat. There may be a sharp physical shock or jolt. Some women, for example, may wake up in the middle of the night with a shock of anxiety and wonder what has threatened them. Some women report other associated sensations such as a racing heart, nausea, and breathlessness. Some feel dizzy, anxious, and unable to concentrate. Others experience cognitions and feelings such as empowerment, anxiety, and catastrophic thoughts.

Flashes are basically not understood. Beneath the scientific generalities, there is no specific understanding of what underlies flashes. They do clearly have something to do with estrogen: they increase in frequency in the years surrounding menopause, and treatment with a hormone medication is helpful. However, while fluctuating estrogen levels are assumed to be causal, clear evidence of this has been notably lacking. Further, flashes are found during the menopausal transition and postmenopausally, two very different hormonal situations, but are not a widespread phenomenon during premenstrual hormone fluctuations. For the minority of women with severe symptoms, there is no understanding that would lead to correction of underlying problems beyond symptomatic treatment with medications like estrogen. Why would a brain center regulating body heat be affected in some women but not others or in the same woman only sometimes? There are speculations that estrogen is needed for brain general health and proper neurotransmitter balance or that some women are “more sensitive” to normal changes in hormone levels. It seems that additional factors must also be at play. The large cross-cultural differences in flash frequency and the large placebo effects of medications are not understood, neither is the role of stress or other psychological or situational factors.

So, I think it’s weird. I think it’s weird to have odd physical experiences like a sudden experience of intense heat or a sharp jolt, even though for most women the experience seems to cause no significant or permanent harm. For women who find these experiences unsettling: why wouldn’t they? It’s almost sensible. The idea that we’re told “it’s just menopause” is weird. Personally, I wish more basic research was being done about what hot flashes are. I wish that more basic research was being done to understand women who have serious problems. As an analogy to the idea that there is “normal pregnancy and childbirth” and there are “complications of pregnancy and childbirth,” which discomforts are “just menopause” and which are “complications of menopause”?


Derry, P.S., & Dillaway, H. (2013).  Rethinking menopause.   In M. Spiers, P. Geller, & J. Kloss (Eds.), Women’s Health Psychology, pages 440-463. New York: Wiley.

2 responses to “Hot Flashes Are Weird”

  1. Hi Paula,
    You did an excellent job of charactarizing the paradoxes of hot flashing and night sweats. They occur in perimenopause when estrogen levels are high and in menopause when estrogen levels are low. They are influenced by how we expect to suffer or cope. And they are mysterious–mostly because we wrongly associate them with low estrogen levels or “estrogen deficiency”. That notion is corrected by: they occur in perimenopause in regularly menstruating women (Hale Climacteric, 2003), and they are effectively treated by oral micronized progesterone (Hitchcock, Menopause, 2012).

    I’d like to add that much of the science is available, it is just not yet integrated.

    The key for me is that the brain can and does become used to (or addicted to) high levels of estrogen. The higher the estrogen exposure, the more likely hot flushes are to occur during short term estrogen drops (withdrawal).
    When estrogen levels drop there is brain release of norepinephrine (and other stress-related brain hormones called neurotransmitters), the thermoneutral zone (temperature range during which we are comfortable and neither sweating nor shivering) narrows to nothing, and a heat dissipation response (blood to the skin, hot hands sweating) occurs.

    Because of the massive discharge of stress hormones we feel anxious, angry, scared (dizzy or nauseated) or just on edge and having trouble concentrating or remembering.

    Another paradox of hot flushes is that, although they are commonly considered just a nuisance, there is increasing evidence that they alter bone and heart physiology. We recently showed that night and day hot flushes differed in their cardiovascular effects (Hitchcock, Menopause 2012) with day ones having generally positive relationships with blood pressure and night sweats having negative relationships. In the Canadian Multicentre Osteoporosis Study, a population-based observational investigation of women ages 43-63, those with night sweats lost hip bone more rapidly than those without (Pinto, Endocrine Society 2007).

    As a person who had to deal with very severe and began when I was still cycing regularly, disturbed my sleep and zapped my resilience, the most important paradox (if you will) of hot flashes/flushes and night sweats is that the ovarian hormone, progesterone, in a pill form (300 mg at bedtime) effectively treated them. We have proven this in a well powered randomized controlled trial (Hitchcock, Menopause, 2012) that showed progesterone also improved sleep and was safe.

    One of the paradoxes of estrogen treatment of hot flashes is that when stopping estrogen (withdrawal), they rebound to worse than ever. Therefore I think of hot flushes in terms of addiction (and the best animal model still is the opioid addicted rodent in withdrawal). The good news is that progesterone withdrawal over one month did not cause a rebound and hot flashes were not yet back to their baseline level (Prior Gynecological endocrinology 2012).

    We’ve learned a lot about weird hot flashes–enough to empower women to cope with or, if needed and chosen, to access effective and safe therapy.

    Since norepinephrine

  2. Paula Derry says:

    I respect your research, and the clinical work you do. However, we disagree about how all of this fits together and what broad generalizations can be made. As is clear from my blog, I don’t agree that the science is known. I think that we have snippets—the thermoregulatory zone can narrow and that’s a piece of the puzzle; estrogen levels can be related to neurotransmitter release; there’s a rebound after discontinuing estrogen medications; your own research has indicated among other things that progesterone can be an effective treatment. But how all of this fits together is unclear. I don’t agree that the explanations are as clear, simple, linear, and grounded in convincing research, as the conclusions you present. I didn’t think that hot flashes were due to low estrogen. Estrogen fluctuations are not always documented accompanying hot flashes and it’s a stretch to say they explain flashing 15 years after menopause. Women may have a rebound effect in which their symptoms return when they discontinue a prescription medication, but medication dynamics, as I’m sure you know better than I, are not the same as the normal functioning of a hormone in the body. Hot flashes are not purely physiological: for example, women may not experience flashes when physiological measurements indicate that flashes are occurring, and may experience flashes when there aren’t measurable physiological changes. There’s insufficient understanding of the determinants of individual differences or what organizes the snippets. Why, for example, would one woman’s thermoregulatory zone narrow while another woman experiences flooding of neurotransmitters that create stress-related physical symptoms while a third has minimal effects? I don’t agree that talking about “addictions” or women who are “oversensitive to normal hormone changes,” etc., answers the question. I wonder sometimes whether it’s because I’m not a physician and am not faced with the responsibility to respond to patients in need that is part of the reason that I feel freer to retain a questioning rather than an action-oriented stance.

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