Medically, the condition of having excessively sweaty palms is known as "Palmar Hyperhidrosis" and it's caused by two different things: emotional stress and your body trying to control its temperature (thermoregulation). The two are closely intertwined, which makes things complicated, so let's make a long story short: When we get excited, scared, or nervous it causes a reaction from your sympathetic nervous system, which stimulates the Eccrine glands on your face, palms, soles of your feet, and in your armpits.