Climate transitions destabilize heat loss

Middle-aged skin may shed heat poorly during repeated shifts between humid heat and dry cool air. This hypothesis asks why blood flow weakens while sweating continues. Its proposed mechanism is temporary receptor desensitization: after one stimulus, receptors that widen skin blood vessels respond less to the next. Sweat glands use a separate muscarinic signal and would keep secreting. Tests would deliver paired stimuli. A short gap should shrink the second blood-flow response; a pause should restore it, while a receptor-bypassing stimulus still widens vessels. Recovery after correcting delay or reordering activation would instead favour timing or spatial explanations.