Sweating is a necessary and natural response to an increase in body temperature. Several things can trigger sweating, including warm temperatures, exercise, or situations that make you angry, embarrassed, nervous, or afraid. Having hyperhidrosis means that you sweat more than usual and often without the typical triggers. Current estimates of the prevalence of hyperhidrosis in the United States are 15.3 million people or approximately 4.8% of the population.