Hot flashes, also known as hot flushes, are sudden feelings of warmth that spread across the body and last from 30 seconds to 10 minutes. They are a common symptom experienced during menopause, affecting as many as 85% of women during this transition. What causes hot flashes during menopause? They are related to decreasing levels of the female sex hormone estrogen. As women approach menopause, their ovaries gradually produce less estrogen. This fluctuation and decline in estrogen levels affects the hypothalamus - the part of the brain responsible for controlling our body temperature. Hence, we get the intense heat, sweating, and redness that often characterize a hot flash. Some key things to know about hot flashes: