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Midlife and Menopause

Hot Flashes, Night Sweats and Sleep Disturbances: The Heat Spectrum

Variously called hot flashes, hot flushes, night sweats, and vasomotor symptoms, sensations of heat during the menopause transition can occur occasionally or frequently and range from mild to intense. For a small number of women, flashing can become a regular occurrence, day and night. For some, these episodes are associated with heart palpitations or a sense of panic or dread.

If you have been experiencing hot flashes for a while now or you’re suddenly finding yourself shedding layers of clothing during an episode, you are not alone. Studies have shown a wide variation in the incidence of hot flashes, from a low of about 35 percent to a high of 80 percent.1 Women who have hot flashes experience them on average for slightly less than four years, but they can persist even longer; a small number of women may still have hot flashes in their seventies and eighties.2

Some women are relieved to feel some heat after years of enduring cold hands and feet.

I have experienced a few hot flashes and night sweats, but nothing too concerning. I’ve been cold all my life, so I welcome a little warmth.

Others view the surges as powerfully sensual experiences. Still other women find the unpredictability and intensity upsetting.

I was experiencing hot flashes to the extent that they were interfering with my business. While doing real-estate presentations for my clients, for example, I’d break out in a drenching sweat and my glasses would fog over. I felt embarrassed.


A hot flash is a sudden sensation of heat, usually in the upper body, that may rise up from the abdomen—or in some cases emanate from the toes—into the chest, back, and head, and may be accompanied by perspiration. Other sensations may include heart palpitations and anxiety. A hot flash may last from about one to five minutes.3 Once the flash is over, some women may also feel chilled. Women with physical disabilities such as spinal cord injuries may experience hot flashes in different parts of the body or only on one side.4

The reasons women have hot flashes have not been fully explained. In the past, doctors postulated that the onset of hot flashes had everything to do with the decrease in estrogen as a woman approached menopause. However, not all women get hot flashes. What’s more, researchers have found that the levels of estrogen do not differ substantially between women who have hot flashes and those who don’t.5

Other factors that may be involved in hot flashes include the body’s core temperature regulation and brain chemicals. The body’s thermostat has an upper set point, at which the body’s blood vessels open up and perspiration occurs, in an effort to release heat. There is also a lower threshold, at which shivering begins to generate heat. Between these two extremes is a temperature zone at which the body normally functions. Doctors now theorize that the zone between the high and low set points in peri-and postmenopausal women who experience hot flashes is narrower than in women who don’t experience any hot flashes. A slight increase in core body temperature, therefore, could be causing a sensitized woman to experience a hot flash as her body tries to reduce its temperature.6 Another factor that could be affecting the body’s core temperature regulation is the brain neurotransmitter norepinephrine. Levels seem to be higher in some peri- and postmenopausal women who experience hot flashes.7


While the terms hot flash and hot flush are often used interchangeably, some experts define hot flushes as the heat that dilates blood vessels, causing some women to turn red in the chest and face. Not all hot flashes are accompanied by flushing.


A night sweat is a hot flash experienced at night that usually causes perspiration in the back of the head and chest and dampens sleepwear, pillows, and sheets. A woman may wake up and have to change her clothing and bedding. Some women may have difficulty falling back to sleep after a night sweat.

I’ve been tracking my night sweats for a few months and sure enough, I get them a lot right before my flow starts. Sometimes, I just roll over to another part of my king-size bed. If that’s not good enough, I flip my duvet from top to bottom to snuggle under a dry patch. If it really gets bad, then I wear my new pajamas, which I made out of that soft cottony fabric that wicks away the sweat and dries quickly.

For night sweats, I found that sleeping in cotton pj bottoms but only a bra on top helped me because there was no wet top to wake me up, which I would then have to take off.

End of excerpt
Excerpted from Chapter 5: Hot Flashes, Night Sweats abd Sleep Disturbances in Our Bodies, Ourselves: Menopause  © 2006 Boston Women's Health Book Collective


1. NIH State-of-the-Science Panel, "National Institutes of Health State-of-the-Science Conference Statement: Management of Menopause-Related Symptoms." Annals of Internal Medicine 142, no. 12 (June 21, 2005):1003-13. [back to text]

2. Nancy E. Avis, Sybil L. Crawford and S. M. McKinlay, "Psychosocial, Behavioral, and Health Factors Related to Menopause Symptomatology," Women's Health 3, no. 3 (Summer 1997);103-20: see also Denise Goldani von Muhlen, Donna Kritz-Silverstein, and Elizabeth Barret-Conner, " A Community-Based Study of Menopause Symptoms and Estrogen Replacement in Older Women," Maturitas 22, no. 2 (September 1995):71-78. [back to text]

3. Fredi Kronenberg, "Hot Flashes: Epidemiology and Physiology," Annals of the New York Academy of Science 592 (June 13, 1990):52-86. [back to text]

4. Claire Z. Kalpakjian, Elisabeth H. Quint, Denise G. Tate, Sunny Roller, and Loren L. Toussaint, "The Experience of Menopause in Women with Physical Disabilities," Final Report, Department of Physical Medicine, University of Michigan, Ann Arbor, May 2004. [back to text]

5. Alexandra Block, "Self-Awareness during the Menopause," Maturitas 41, no. 1 (January 20, 2002):61-68; see also J. D. Hutton, H. S. Jacobs, M. A. F. Murray, and V. H. T. James, "Relations between Plasma Oestrone and Oestradiol and Climacteric Symptoms," Lancet 311, no. 8066 (April 1, 1976):678-81. [back to text]

6. Robert Freedman and Willane Krell, "Reduced Thermoregulatory Null Zone in Postmenopausal Women with Hot Flashes," American Journal of Obstetrics and Gynecology 181, no. 1 (July 1999): 66-70. [back to text]

7. K. Bruck and E. Zeisberger, "Adaptive Changes in Thermoregulation and Their Neuropharmacological Basis," in E. Schonbaum and P. Lomax, eds. Thermoregulation: Physiology and Biochemistry (New York: Pergamon, 1990), 255-307.  [back to text]

Excerpted from Our Bodies, Ourselves: Menopause, © 2006, Boston Women's Health Book Collective.

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