The answer to this question of the ages is found within an insightful, detailed 3,800 word article by Tara Parker-Pope over at The New York Times. Although lengthy, it explores the research into this issue and focuses on the work by Ronald Glaser and Jan Kiecolt-Glaser from Ohio State University who’ve been studying the intersection of psychology on the biology of humans since the 1980s:
The two scientists were fascinated by each other’s work, which they often discussed over meals or while jogging together. Glaser suggested that they collaborate professionally, but finding common ground was a challenge: he studied virology and immunology; she was a clinical psychologist who focused on assertiveness and other behavior. In the early 1980s, however, Kiecolt-Glaser came across a book on the emerging field of psychoneuroimmunology, which concerns the interplay between behavior, the immune and endocrine systems and the brain and nervous system. The couple were intrigued by a science that lay at the intersection of their disciplines. […]
In their first research collaboration, they sought to measure the effect of psychological stress on the immune system. Although earlier studies had established that trauma and other major stress — like the death of a loved one or prolonged sleep deprivation — weakened the immune system, the Glasers wanted to know if lesser forms of stress, like those associated with the workplace or graduate school, had a similar effect.
Who would’ve thought that two scientists in unrelated fields would find a way to work together like that?
“Have the psychiatrists gone mad? — those who weren’t crazy to begin with! They want to turn grief into a disease!”