Why can hot flashes be followed by chills or shivering?

Hot flashes and subsequent chills occur because declining estrogen levels interfere with the hypothalamus, the region of the brain that functions as the body's thermostat.12

During menopause, the hypothalamus becomes overly sensitive to even minor temperature fluctuations. It may mistakenly signal that the body is too warm, triggering rapid cooling responses such as the widening of blood vessels (vasodilation) and perspiration. As the body attempts to cool down, it may overcompensate for this perceived heat. This "overshoot" of the cooling response often leads to a subsequent sensation of cold and shivering.234