Psychoneuroimmunology
Psychoneuroimmunology (PNI) is the study of how the mind and the nervous system interact with one another. Its main area of interest is the effect that thought, particularly, stressful thoughts, have on the immune system of the body, and it has been particularly applied to the study of autoimmune diseases.
In other words, PNI is about mind over matter, and about how much influence the mind does actually have over matter i.e. the physiological functioning of the body relating to health and wellbeing.