Perimenopause temperature dysregulation goes far beyond hot flashes. When estrogen fluctuates, KNDy neurons in the hypothalamus become overactive — collapsing the thermoneutral zone and triggering inappropriate heating and cooling responses. Cold flashes, sudden chills, and unpredictable temperature swings are real, documented vasomotor symptoms. Cathy breaks down the neuroscience and what the evidence actually supports for fixing it.