Women make men better (Getty Images )

In a recent study, the scientists measured the heart rates of 32 couples who stared at each other for 3 minutes without touching or speaking. The result: Close companions showed similar heart rate patterns and breathed in and out around the same times. What's more, when the participants swapped partners (fun!), heart rates and breathing patterns didn't match anymore.
Researchers think that when you and your mate are in sync emotionally, it also manifests through other channels, like physiological responses. And if that's not bizarre enough, here are four more weird effects she has on you. Don't worry: Most of them are good! (Men are from Mars, and women are...also from Mars, according to these 3 Myths about Women You Shouldn't Believe.)

1. You Don't Stand Next to Hot Women Anymore
A study published in the Journal of Neuroscience found that men in relationships prefer that attractive women keep their distance. In one study, a group of men--some single, some taken--were given a dose of oxytocin, also known as "the love hormone." Then they had an attractive female researcher approach the participants. The woman asked the men to speak up when they thought she was at an "ideal" distance from them. The result: Tied-down dudes had bigger personal bubbles, preferring the hot scientist to stay about 28 to 30 inches away from them, while single guys liked her about 20 to 24 inches away. Blame oxytocin, which is released when you cuddle, kiss, or hold hands. Researchers think if you're committed, it boosts your fidelity, literally leading you to distance yourself from other potential options.
(Want to gawk at more gorgeous ladies? We have the defining list of The Hottest Women for 2013.)
2. Your Emotions Enter a Tailspin
A recent study in the Journal of Health and Social Behavior found that you could be the more emotional one in the relationship, not her. While ladies may take a breakup worse, guys are more stressed when there's trouble in paradise. But you also experience more of an emotional boost when things are going well with her. Why? Since women generally have larger support systems than guys, your relationship with her could be your main source of intimacy, exaggerating the good and the bad.