Immunology: The pursuit of happiness

In 1964, magazine editor Norman Cousins was diagnosed with ankylosing spondylitis, a life-threatening autoimmune disease, and given a 1 in 500 chance of recovery. Cousins rejected his doctors' prognosis and embarked on his own programme of happiness therapy, including regular doses of Marx Brothers films, and credited it with triggering a dramatic recovery. He later established the Cousins Center, which is dedicated to investigating whether psychological factors really can keep people healthy.

At the time, mainstream science rejected the idea that any psychological state, positive or negative, could affect physical well-being. But studies during the 1980s and early 1990s revealed that the brain is directly wired to the immune system — portions of the nervous system connect with immune-related organs such as the thymus and bone marrow, and immune cells have receptors for neurotransmitters, suggesting that there is crosstalk.

http://www.nature.com/news/immunology-the-pursuit-of-happiness-1.14225