They can hit as often as every 90 minutes. Each one can last from 15 seconds to 30 minutes - 5 minutes is average. Seventy-five to eighty percent of women going through menopause experience hot flashes. Hot flashes bother some women more than others. Sometimes heart palpitations accompany hot flashes.
Hot flashes occur sporadically and often start several years before other signs of menopause.
They gradually decline in frequency and intensity with 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.