Seventy-five percent of the women in the United States experience hot flashes of some kind as they approach menopause and for the first year or two after their periods stop. Between 20-50% of women continue to have them for many more years. Most women have mild to moderate hot flashes, but about 10-15% of women experience such severe hot flashes that they seek medical attention. As time goes on, the intensity usually decreases.
Whether you've had breast cancer or not, there is considerable variation in time of onset, duration, frequency, and the nature of hot flashes, An episode can last a few seconds or a few minutes, occasionally even an hour, but it can take another half hour for you to feel like yourself again. The most common time of onset is between six and eight in the morning, and between six to ten at night.
When hot flashes hit in the middle of the night, they’re called night sweats. Your body temperature tends to go down a bit as you sleep. With a lower estrogen level in the body, your brain gets tricked into thinking that it’s time to heat up the body. You start perspiring to get rid of the heat and you wake up soaked.