Your skin becomes red and warm and your heart may pump faster. During an intense hot flash, you may have a red face and perspire excessively. During a mild hot flash, you may just feel a warm flush. A typical hot flash lasts from 1 to 5 minutes. However, a hot flash can last up to an hour.
Night sweats refer to a hot flash at night accompanied by profuse sweating.
This makes it difficult to sleep, leading to tiredness during the day. The exact cause of hot flashes and night sweats is not known. However, hot flashes are related to the decrease in estrogen. One theory is that estrogen affects your brain's ability to regulate your temperature. During a hot flash your body thinks that it is too hot, and is trying to cool down by sweating and opening blood vessels to release heat.