According to the research carried out by the scientists of the American University of Leoma, that were studying, in 2006, the interaction between the brain, behaviour and the immune system, it was discovered that the honest laughing stimulates the excretion of the health-protective hormones.

After such discovery, the same scientists, in 2008, came to a notion that laughing also reduces the level of harmful stress hormones.

When exposed to hilarious video clips, the individuals experienced the significant increase of beta endorphin hormone, which is, by the way, responsible for soothing of depression, as well as the human growth hormone, which protects the immunity. On the other hand, the group of individuals that was not exposed to hilarious video clips recorded no changes in the level of the hormones.Besides, similar researches have demonstrated that laughing reduces the level of three stress hormones, which means that the level of cortisol, adrenalin and dopamine catabolite was significantly reduced.