In the experiment, researchers showed two movies, one humorous and the other stressful to 20 healthy volunteers and monitor the blood vessels’ reaction. The researchers specifically looked at the endothelium, the linking of the vessels, and found that the blood flow was reduced 35% in 14 of the 20 volunteers after watching the stressful movie clips. However in 19 of the 20 volunteers who laughed at the funny movie segments, blood flowed 22% more freely.
