The Flip Side
Hot flashes in menopause occur when hormone levels fluctuate, affecting the body's temperature center in the brain, the hypothalamus. When the hot flash occurs, blood vessels in the skin dilate to encourage heat to dissipate. It may also start a perspiration reaction to cool the body down. When the hot flash subsides and the skin is still wet and clammy, many women experience chills and shivering, often as severe as the hot flash counterpart.
Though not as common as a hot flash, some women experience only a cold flash, with or without the sweat. It can last for minutes, hours or days. For some, even hot drinks, hot baths or blankets are not enough to relieve the chill. Often, the measures taken to relieve the cold flash will lead to a hot flash and once more to chills. Again, the temperature-regulatory center in the brain is responding to fluctuating hormone levels.
The Thermoneutral Zone
Robert R. Freedman, a professor of psychiatry and behavioral neurosciences at Wayne State University in Detroit, in a 2002 article published online by the North American Menopause Society, describes a study that suggested a "narrowed thermoneutral zone" in menopausal women. The thermoneutral zone is the body temperature at which neither sweating nor shivering takes place. When body temperature rises above or below a certain threshold, we sweat or shiver respectively. In this study of symptomatic menopausal women, the shivering threshold was higher and the sweating threshold was lower, reducing the thermoneutral zone, so that even slight changes in core body temperature caused a hot flash or chills.
Stress, caffeine, nicotine, alcohol, food additives and being in warm places can all trigger hot flashes that may lead to chills. Similarly, cold drinks, cold weather and emotional turmoil may trigger a cold flash, though it is entirely possibly to experience a cold flash when the ambient temperature is hot and vice versa. Sometimes, unfortunately, there is no trigger at all except your changing body.
What To Do?
First, avoid hot flashes that lead to chills by cutting out smoking and caffeine. Avoid spicy foods. Dress in layers, and keep the thermostat down. For cold flashes, try hot drinks, hot baths, sweaters or blankets. Keeping feet and hands warm can often help warm the rest of the body. Have warm slippers available that you can easily slip into and out of as your body temperature fluctuates. If the episodes become too disruptive, don't be afraid to see your doctor, who may be able to prescribe medication or alternative remedies to even out your body-temperature roller coaster.