There are two kinds of stress--distress, which is the negative kind of stress; and eustress, which is the positive kind of stress. While distress increases stress hormones such as beta-endorphin, corticotrophin, cortisol, growth hormone, prolactin, and the catecholamines, eustress decreases these hormones and instead increases the activity of Natural Killer (NK) cells that help fight diseases (Berk & Tan 1996). Distressful events and major life changes can obviously impact our bodies negatively. It has been proven that stress depletes the immune system's ability to fight against disease. Dr. Lee Berk and Dr. Stanley Tan of the Loma Linda University Medical Center have done an abundance of research in psychoneuroimmunology (PNI). PNI simply says that the immune system is directly connected to the brain; therefore, it would be effected by the emotions. One of Berk and Tan's experiments showed that immunosuppressive hormones (hormones that harm or deplete the immune system) such as epinephrine and cortisol were lower in those participants that laughed than in those who did not (Wooten 1995). Another experiment performed by Berk and Tan (1996) in which they presented their results at a conference on April 18, 1996, proved that laughing (while watching a humorous video) increases the amount of NK cells.
Indirectly, stress is probably our number one killer. It effects us physically and mentally, wearing our immune systems down, and causing us to be more susceptible to sickness and disease. We try to treat the disease, when we really need to treat the cause. How does one treat something like stress? Many times the stressors cannot be removed from a person's life; they are permanent fixtures. Laughter, if used generously, can help drain the stress away. As Mark Twain once said, "The human race has only one really effective weapon, and that's laughter. The moment it arises, all our hardnesses yield, all our irritations and resentments slip away, and a sunny spirit takes their place."