6 Fascinating Things That Happen To Your Body When You’re Making Out With Someone

A 2007 study published in the journal Evolutionary Psychology found that kissing has three main functions: assessing a potential mate, initiating sexual activity, and bonding. According to Dr. Jill McDevitt, resident sexologist at CalExotics, a passionate kiss can increase the production of the love hormone, oxytocin. This triggers attachment between couples. Making out with someone you like can also lead to a boost of dopamine, which is responsible for desire, and serotonin, which can possibly lead you to have obsessive thoughts about your partner.

"There's a theory that our nose smooshed in our kissing partner's face makes their pheromones more obvious," Dr. McDevitt says. Whether you realize it or not, your body will react to your partner's phermones and can possibly make you even more attracted to them. At the same time, your body can also reject your partner's "scent" and cause you to feel less attracted to them. This may be the reason behind why you may feel like a first kiss with someone new is "bad." It's your body's way of telling you that something in their genes is just not a good match.

There are some pretty good health benefits associated with kissing. According to Dr. McDevitt, stress reduction is one really great benefit, "especially if you're present and enjoying the kiss." In fact, a 2005 study published in the Neuroendocrinology Letters found that kissing has a way of reducing your stress hormones. The feel-good hormones that get released when you're making out with someone can counteract the ones that bring you down.

It's no surprise that kissing can cause you to get sick. As Caleb Backe, health and wellness expert for Maple Holistics, tells Bustle, "The human mouth is filled with so much bacteria, more than six billion in fact, that doctors refer to it as the 'human oral microbiome.'" Interestingly enough, kissing is one of the ways humans evolved to strengthen their defenses and boost their immune systems. According to Backe, the "microbial communities" that get swapped with your partner when you're making out help to introduce foreign agents into your body, which prompt the immune system to produce new antibodies. "A ten-second kiss can transfer as much as 80 million bacteria," he says. Don't worry, it's meant to be good for you.

When you're attracted to someone, your pupils are known to dilate. When you're kissing someone you're attracted to, the same thing happens. "The more attracted and aroused you are the more your pupils dilate," David Barbour, co-founder of Vivio Life Sciences, tells Bustle. "Perhaps even part of the reason people close their eyes while kissing is an increase in light sensitivity and blurred vision." Those are two things that tend to happen when your eyes get dilated.

There's no doubt that making out with someone for a good amount of time can be super arousing. But according to Good Vibrations' staff sexologist Carol Queen, PhD, it doesn't just stop there. "A lot of people assume that orgasm is a strictly genital response," she says. "But even though most orgasms are generated in response to genital stimulation, an orgasm is a neurological response that happens in the brain — kissing can be plenty neurologically and erotically stimulating." That's because the mouth and the tongue are rich in nerves. If all the other conditions are right (i.e. you're attracted to the person and they're kissing you in a way that you like), "a full-on orgasm can definitely result," she says.

Kissing is more than just getting up close to someone and exchanging saliva. So keep these in mind the next time you're in the middle of a make out session.