You could sweat when you're anxious to alert others. One theory suggests we've evolved to sweat whilst anxious to alert the brains of other people around us so they are primed for whatever it is that's making us anxious. Brain scans have revealed that when you sniff the sweat of a panic-induced person, regions of the brain that handle emotional and social signals light up. When you're anxious your sympathetic nervous system releases hormones including adrenaline, which activates your sweat glands.