Medical Student Studies: Do Small Stresses Really Matter?
Kiecolt-Glaser, J.K., & Glaser, R. (1993). Mind and immunity. In: D. Goleman & J. Gurin, (Eds.) Mind/Body Medicine (pp. 39-59). New York: Consumer Reports.
When PNI researchers first turned from rats to human beings, they began by examining the effects of very intense events on the immune response. For example, they found altered immune function in astronauts at the end of their mission; in Swedish volunteers who endured 77 hours of noise and sleep deprivation; and in people whose spouses had recently died. (All these studies showed decreases in the response of immune system cells to stimulation in the test tube.)
While the physical response to such extreme events is interesting, it's not immediately relevant to everyday life; fortunately, no one loses a spouse or goes for three days without sleep very often. But a decade ago, only a handful of PNI researchers had used human subjects--the vast majority of studies were still being done on rodents--and virtually all the human studies looked at the effects of extreme stress.
It was at that point that we began our research, which has been aimed at studying the connection between stress and immunity under more natural circumstances. Although we were married, we had never thought about working together. One of us (Janice Kiecolt-Glaser) was a psychologist whose research had focused on assertiveness training, while the other (Ronald Glaser) was an immunologist studying the possible role of Epstein-Barr virus in a form of nasal cancer. While our relationship was based on many things, the prospect of professional collaboration was not one of them.
But as we began to become aware of the growing body of research in PNI--which we each saw through the lens of our respective backgrounds--we realized that we had a unique opportunity to pool our disciplines and make a contribution together. In 1982, we began clinical studies at Ohio State University to try to synthesize the tantalizing but scattered findings on stress and immunity and to investigate their relevance to human health.
We reasoned that if stress was indeed an important risk factor for infectious disease (and perhaps for cancer as well), then immunological changes should be associated with ordinary stressful events as well as intense ones. To find out, we began conducting annual studies of medical students. Every year from 1982 through 1992, we collected immunological and psychological data from the students throughout the academic year, including the three-day period in which they take their examinations. We found that the simple stress of exams adversely affects a very wide range of immunological functions.
For example, we found that exams brought about a decline in the activity of natural killer cells--the cells that fight tumors and viral infections. The body's production of an immune system chemical called gamma interferon, which stimulates the growth and activity of NK cells, decreased by as much as 90 percent during examinations. The medical students' T-cells also showed a poorer response to test-tube stimulation during examinations.
In one of our medical-student studies, we placed catheters in students' arms for 24 hours during a low-stress academic period, and then again during exams, so we could draw hourly blood samples to measure changes in stress hormones (which can affect immunological activity). Nurses waited outside the students' classrooms during the day in order to get their hourly samples, and students slept in the university hospital's research unit at night. William Malarkey, the endocrinologist who conducted the hormone studies, found that levels of adrenaline and noradrenaline increased significantly at exam time, during both waking and sleeping hours. These changes could have led to some of the immunological changes we have observed. All these findings are especially meaningful when you consider that medical students are experienced at taking examinations; the simple fact that they have been admitted to medical school shows that they have repeatedly done well on college exams. Yet despite their relative competence in this stressful situation, it consistently regulates their immunological function to a lower level.
Are these studies relevant to those of us who no longer take exams? We think so. The stress of examination should actually provide a good model for understanding people's responses to other commonplace stressors-events that people experience on a fairly routine basis but that still cause stress. For example, the several days before you go on a vacation or a business trip are often filled with frenzied activities at work and at home. Your emotional response to the pressures of those periods may be quite similar to the medical students' feelings of stress and anxiety as they cram for exams. Similarly, you may feel tension or strain if you have to spend several days in the company of your least favorite relatives. If the stress you experience in these common situations is similar to our medical students' responses to academic pressures, your immune system, too, may show the effects.
By learning how to relax, however, you may be able to affect your immune system's functioning. In one study, we took 34 medical students before exam time and randomly assigned half of them to a group where they were given hypnosis and relaxation training. During exams, we compared the immune function of students in the training group with that of the other students, who received no such training. We saw no difference at first: Students in the relaxation group showed the same average downward alterations in immune function as the others. But a closer look showed that the students trained in relaxation varied tremendously in how often they practiced their relaxation techniques. And those who took their relaxation seriously, who practiced the techniques often, showed significantly better immune function during exams than did those who practiced less frequently or not at all.