Dr Cohen and his friends of the Carnegie Mellon University of Pittsburgh (PA) gathered 334 healthy volunteers aged 18 to 54 years. They categorized them in 2 sets : the "positive" on one side (happy, glad, dynamic and sociables) and the "negative" on the other side (dissatisfied, stressed and especially grousers). Then, they gave them nasal drops containing a rhinovirus. During 6 days, researchers collected data on the health of the patients. Objective data like the production of mucus but also of subjective data like the complaints of pains, cough, etc.

Results: The tendency to experience positive emotions was associated with greater resistance to objectively verifiable colds. In other words, the group "positives" fight the virus better than the group "negative". Moreover, but that's more obvious, the "negatives" complained more easily about symptoms than the "positives", at "equal disease".

The researchers show that the joy, not the self-esti or the optimism, can explain these effects. They speak about objective reasons like the fact that the joy boosts the immune system, and subjective reasons like the fact that happy people are less worried about a cough or a noise which falls.

Today, looking at grousers, just think that they maybe won't survive this winter ... and smile :)