Whether you're relieving your stress through kickboxing, playing a basketball game with friends or just running through a meadow of flowers on a perfect spring day (which is totally how all our runs go, right?), you know that working up a good sweat can definitely improve your mood. But did you know that just being around someone drenched in "happiness sweat" can make you feel happier too? According to a surprising new study published in Psychological Science, a good mood is not only contagious, it can spread through our fragrant pit juices.

Researchers took healthy young men, taped moisture-absorbing pads to their underarms, then had them view a movie that made them feel happy, afraid, or neutral. The sweaty pads were then given to women who sniffed them while the scientists monitored their facial expressions. Sure enough, women who sniffed the happy sweat showed genuine smiles while women who sniffed the fear sweat showed indications of being anxious.

"This suggests that somebody who is happy will infuse others in their vicinity with happiness. In a way, happiness sweat is somewhat like smiling—it is infectious," said Gün Semin, a psychological researcher at Utrecht University in the Netherlands and the lead author of the study. (Think this is strange? See more 8 Weird Things That Are Contagious.)

The researchers think it is a form of chemical signaling, a way of communicating emotion and intention to others in a very subtle and primal way. Indeed, the women in the study didn't report feeling differently when asked how they were doing, although they did show facial expressions of happiness after smelling the happy pit juice and were better able to focus on tasks (a sign of genuine happiness according to the psychologists). According to Semin, this shows the difference between emotional signals that draw on language versus those that don't.

More research still needs to be done, the researchers caution, but the implications are as exciting as they are smelly. For instance, this might explain why women bond so well when they work out or play sports together. At the very least, it should inspire you to give your loved one a huge hug the next time they cross the finish line. Even if they do get you all sweaty, you'll be reaping the endorphins reward! (Sounds like a great excuse to hit the gym with your friend! Here's Why Having a Fitness Buddy Is the Best Thing Ever.)