Hot Flashes
A widespread discomfort of menopause and perimenopause, hot flashes affect about 75 percent of menopausal women. These women report various experiences of the phenomenon, ranging from a glowing sensation to a burning heat, usually with some sweating, which may be particularly bad at night (night sweats). The frequency of the hot flashes also differs greatly: some women have a few mild hot flashes a week for a short period, while others may experience up to 50 a day for many years. In very severe cases, they may occur six or seven times in an hour.
Many women experience hot flashes well before their last menstrual period. Initially, these are infrequent and are on the face, neck and chest only. Over time, these flashes can become more frequent, last longer, and they may continue to occur, with occasional flush-free periods, for up to five years.
What Causes a Hot Flash?
The underlying physiology of hot flashes is complex, but the onset of a flush may correspond with an increase in the level of the pituitary hormone, follicle stimulating hormone (FSH). Significant changes in levels of FSH secretion are common as menopause approaches, and they appear to be a response to the shrinking of the ovaries and decreased estrogen secretion.
The loss of estrogen itself makes the blood vessel muscles more unstable, hence the term ‘vasomotor instability’, which is sometimes used to describe a hot flush. Other internal secretions also surge during a hot flush. For example, there is a significant rise in the blood level of some of the adrenal hormones.
More simply stated, a hot flush occurs because the brain decides your body is overheated. During menopause, your temperature-regulating system changes. Your sweat glands may work less effectively than before because lack of estrogen changes the way they are programmed. Not only do your sweat glands not cool as efficiently as before, but there also appears to be a change in brain chemistry that affects the temperature control centre in the hypothalamus. The temperature set point becomes lower than normal, and this triggers a dilation of blood vessels in the skin and sweating as your body attempts to reset its thermostat. The adjustments aren’t always smooth and your body often overcompensates, hence hot flashes.
