Why do hot flashes happen?

Hot flashes occur when declining estrogen affects the hypothalamus, the part of the brain that regulates body temperature. This makes the body more sensitive to small changes in temperature, triggering a sudden feeling of heat, flushing, and sweating as the body tries to cool itself down.

Hot flashes can vary from mild warmth to intense heat with a racing heartbeat, and they often occur more frequently at night as night sweats.