Sure, we've always gotten a tingly, head rush when we kiss someone we're attracted to, but we never knew that swapping spit caused such a complicated hormonal rickashay.

During a recent study at Lafayette College, researchers studied the cortisol and oxytocin levels in 15 heterosexual, kissing couples. Cortisol, known as the stress hormone, is released to help the body get back to normal after a rush of agonizing events. Oxytocin, on the other hand, is the hormone to blame for all those girly, gooey feelings of closeness after sex.

It's often been said that women release oxytocin after doing the nasty and men don't—the physiological reason behind feeling a little miffed and used when he doesn't call.

Surprisingly, it seems this study proved just the opposite about men and women. While both sexes saw a drop in corisol  while kissing, it appeared that only men experienced a raise in oxytocin. Women—forever desiring more, more, more—needed "a romantic atmosphere of dimmed lights and mood music" to notice any cortisol upswing.

We love this. This inherent appreciation of candle-lit dinners and nice bed sheets—it's in our blood we tell you! Guys, I hope you're reading, this is some important, learned stuff.

Scientists aren't sure why this happens. They think maybe because of pheromones (but we don't really buy that those exist). Most likely it's because, as scientists point out, kissing boosts the body's immune system due to all the mixing and matching of different strains of saliva. 

So, just try to tell yourself that next time you make out with someone you regret—they may have helped you fight off a future cold or flu virus.