Estrogen and progesterone affect virtually all tissues in the body, but everyone is influenced by them differently. A hot flash is a sudden sensation of intense heat in the upper part or all of the body. The face and neck may become flushed, with red blotches appearing on the chest, back, and arms. This is often followed by profuse sweating and then cold shivering as body temperature readjusts. A hot flash can last a few moments or 30 minutes or longer.
Hot flashes occur sporadically and often start several years before other signs of menopause.
They gradually decline in frequency and intensity as you age. Eighty percent of all women with hot flashes have them for 2 years or less, while a small percentage have them for more than 5 years. Hot flashes can happen at any time. They can be as mild as a light blush, or severe enough to wake you from a deep sleep. Some women even develop insomnia.