There are three kinds of sweat: sweat from heat, sweat from exercise and sweat from stress. Of the three, stress sweat is the hardest to control and gives off the foulest stench. If you have trouble keeping your cool in stressful situations, it’s not just bad luck—you’re biologically programmed to stink under pressure.Under normal circumstances, perspiration is meant to cool you down so you don’t overheat. When it’s hot or you’re exerting yourself physically, your temperature gradually rises. Your body’s internal thermostat, located in the hypothalamus, eventually recognizes that it better do something to chill you out and triggers the release of neurotransmitters that instruct millions of eccrine (sweat) glands all over your body to produce sweat. As the sweat evaporates, it carries heat away from you, cooling you off. Voilà.QUIZ: Measure Your StressIt’s a whole different story when you are about to give a speech, stuck in traffic on the way to the airport, or waiting for your blind date to show. Nervous excitement causes adrenaline and cortisol to rush into the bloodstream, raising your heartbeat and unleashing an instantaneous torrent of sweat from your eccrine glands and other glands called apocrine glands, located in your armpits and pubic region. (Apocrine glands are also found in a third location, the ear canal, where they help keep ear wax waxy.)There’s no warm-up period. You go from zero to sweaty in seconds flat. Suddenly you’re drenched—and that stresses you out even more. “If you’re standing out in 100-degree weather, it’s a gradual increase, and anyone else is going to sweat. You expect it,” says Susan Biehle-Hulette, Ph.D., a biochemist at Procter & Gamble. “Conversely, if all of a sudden you have to give a presentation and you’re put on the spot, you are then the only one sweating.”MORE: We Tested These Deodorants (So You Don’t Have To)And stinking. Any sweat can cause body odor, but the smell of stress sweat comes on real strong, real fast. When you sweat, you feed the bacteria that live naturally on your skin. Their digestion produces an unpleasant aroma that we all know as B.O. How bad the B.O. is depends in part on what and how much you feed them. While eccrine secretions are 99 percent water with some electrolytes tossed in, apocrine sweat is 20 percent fats and proteins. If you were to put it in a glass it would look like coffee creamer. Bacteria go nuts for the stuff. They feast on it, and you’re left wafting the pungent aftermath.Research into the function of the apocrine glands suggests an evolutionary role in the fight or flight response. “When a lion is chasing you, you want to smell bad so they don’t eat you,” Biehle-Hulette explains. Studies also show that people can subconsciously recognize the difference between fear sweat and regular sweat, suggesting that it can act as a peer-to-peer danger alert system.In our largely lion-free world, however, the protective value of stank is nil, while the social consequences are high. When Biehle-Hulette led the research team that developed Secret’s Clinical Strength antiperspirant deodorant, the top concern they heard from women in their focus groups was the smell of stress sweat. So they designed the product to address the problem at a chemical level, not just mask the funk with fragrance. Secret’s secret is a patented donut-shaped molecule that physically traps odor molecules, like Febreze for pits.MORE: Boost Confidence with this One-Minute Trick“Sweating from anxiety is a natural physiologic response, and the best thing to do”—if you want to prevent wetness in the first place—”is to try to reduce the anxiety,” counsels endocrinologist Tamara Wexler, M.D., a spokesperson for The Endocrine Society. Well, easier said then done. You can take some deep breaths, bolster your confidence with positive mantras, do a psych-up dance in the ladies’ room. Or you can flip the script on your anxiety and use it to your advantage.Jeremy Jamieson, Ph.D., studies social stress at University of Rochester. “The only way our stress response systems get information about stressful situations is through the lens of perception,” he says. “In situations that we don’t particularly like, like public speaking or test taking, the signs of arousal (sweaty palms, racing heart, etc.) are interpreted as signs of nervousness. However, those exact same signs of arousal might be interpreted as excitement if experienced in a different situation, like before a sporting event. The way we appraise our body’s responses—and our ability to cope more generally—directly impacts how we respond to stress.”You could take your pounding heart as a bad sign, or as an indication that your body is ready for action, “marshaling resources, pumping more blood to our major muscle groups and delivering more oxygen to our brains.” Jamieson ran an experiment in which he stressed people out by making them deliver an impromptu five-minute speech on their personal strengths and weaknesses to two very unimpressed-looking judges. Half of the participants were told beforehand that the body’s stress response was beneficial, and instructed to “reinterpret your body signals” as positive instead of negative. At the end of the study, the people who went into their speeches thinking of jitters as a performance enhancer showed enhanced performance. Their hearts pumped more efficiently and their blood vessels weren’t as constricted. They also said they felt more equipped to handle the stress of the task than the other group.RESEARCH: When Stress is Good for YouIt’s possible that reframing anxiety as an asset could also make you sweat—and stink—less. And if you still get a little B.O., you can reinterpret it as the not-so-sweet smell of success.