Summer is upon us, so the likelihood of being stuck in someone’s armpit during rush hour on the tube is almost definite. It's not the type of environment that makes me grin from ear to ear - more like grimace - but according to a study published in Psychological Science, working up a good sweat can not only improve your mood, but the mood of those around you. 

As with most things that boggle my mind, it comes with a catch. The sweat has to be "happy sweat" (who knew such a thing even existed?). According to a quick google search, happy sweat forms during things like running with your friends in the park or playing a game of volleyball on the beach. 

Question is, how does one come about such science? Well, it involves a lot of healthy young men, their underarms, tape and moisture-absorbing pads. Stay with me... 

After watching a film that would make them feel happy, afraid or neutral, the sweaty pads were given to women who sniffed them while scientists monitored their facial expressions. Grim. The women who sniffed ‘happy sweat’ showed genuine smiles, while the women who sniffed ‘fear sweat’ showed signs of anxiety.

"Being exposed to sweat produced under happiness induces a simulacrum of happiness in receivers, and induces a contagion of the emotional state,” says Gun Semin, a psychological scientist at the Utrecht University in the Netherlands and a senior researcher on the study. "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."

Feeling a bit down? No sweat, just stand next to someone championing patches.