In a small study of medical students, Houston researchers found that during exam time, the anxious test-takers showed increased activity in their DNA repair systems. The DNA repair system jumps into action when there is damage to cells' genetic material. If the damage is beyond repair, the cell commits suicide. All of this is part of the body's normal quality-control system that keeps its machinery running smoothly.

The jump in DNA repair among these students suggests that exam stress might have led to an increase in DNA damage, researchers report in a recent issue of the Journal of Behavioral Medicine.Dr. Gailen D. Marshall, Jr. of the University of Texas-Houston Medical School led the study. Marshall and his colleagues studied 16 medical students' DNA repair during the third day of a 5-day exam period and again 3 weeks later, after winter break. The researchers took blood samples from the students to observe their DNA repair capacity and questioned them on their stress levels.

Not surprisingly, the students reported higher stress levels during exams than they did after vacation. More significantly, the investigators discovered that DNA repair increased during exams for 12 of the 16 students.

These students were showing a healthy response to DNA damage, Marshall explained in an interview with Reuters Health. And while some research suggests everyday stress may increase susceptibility to infections such as colds, healthy people will recover from the short-term DNA damage stress can trigger, Marshall said. He and his colleagues are now delving into the relationship between chronically high stress levels and cancer.

Scientists believe that a faulty DNA repair system may open the door for cancer cells to grow in the body. If stress triggers DNA damage and the repair system cannot respond adequately, Marshall explained, a stressful life may contribute to cancer development in some people. It is also possible that in cancer patients, chronic stress could affect DNA repair and, therefore, the progression of the disease. Marshall's team is currently studying whether cancer patients' stress levels are related to their DNA repair capacity.