Pick a stage · drag sideways · space for a small rise
Core
+0.00 °C
Zone
0.4 °C
Flashes
0 / h
Skin
+0.0 °C
Core temperature, as a change from restSweating threshold (upper jaw) and shivering threshold (lower jaw)Heat let out through the skinYour brain holds core temperature inside a band, the thermoneutral zone: above it you sweat and flush, below it you shiver. In lab studies the zone was about 0.4 °C wide in women without hot flashes and close to 0.0 °C in women with them, mostly because the sweating threshold sat lower. Falling estrogen is thought to narrow it through neurokinin B signalling in the brain.In the leading explanation, on a narrow zone a rise of about 0.04 °C, too small to feel, sets off the whole response: finger skin warms by about 2.7 °C, heart rate rises by about 10 beats a minute, and a typical flash lasts about 3.4 minutes. Core temperature then dips, and some women feel a chill.A typical pattern from small studies, not a diagnosis; not every woman's zone narrows, and many have no hot flashes. Time runs at about a minute a second with quiet spells cut. Flashes per hour come from the model, set for a woman with frequent flashes (about one an hour); the size of the after-chill is illustrative.