7 incredible scientific things that happen to Your Body When You Kiss Someone

Ever wonder why you get butterflies in your stomach during a first kiss? It has everything to do with that stress response. "Your biological stress system is actually activated when you have your first kiss," Seiter says. "But, this doesn’t mean you’re stressed out. You’ll experience increased heart rate, sweating, or butterflies in your stomach; a physiological excitement response." It's the nervous system at work again, which results in "biological fireworks," Seiter says, or the feeling of butterflies in your stomach.