There is proven to be correlation between stress & illness. Stress can cause problems with the circulatory system, problems such as high blood pressure, coronary heart disease caused by atherosclerosis and stroke.
Kiecolt-Glaser et al (1995) supported the link between stress and illness. The study showed the slowing of wound healing in relation to psychological stress (especially how stress damages the immune system). He took 26 participants, recruited by volunteer sampling, in a field experiment; all were given a small cut into their arms. Participants were given a stress scale up to 10, and were asked to state how stressed they felt. Levels of cytokines were also taken from all participants. The participants in the experimental group, consisted of 13 women aged between 47 & 81 years old looking after a relative with Alzheimer's disease. The control group was matched with the carers on age & income. The tests indicated that the experimental group showed higher levels of stress than the control groups. Healing wound time was assessed by photographing the wound regularly and by observing the response to hydrogen peroxide. The time take for the wound to heal was a lot longer for carers (48.7 days) compared to the control group (39.3 days) and also were significantly a larger average size.
Another researcher who found a supportive link between stress & illness was Russek (1962), who aimed to find a link between work-related stress & heart disease. He tested Medical professionals and labelled them as high-stress or low-stress according to their role. GPs (high-stress) had the greatest rate of heart disease (11.9%) and dermatologists (low-stress) had the least heart disease (3.2%). This showed that there is a link between heart disease and stress within a job. However the dermatologists may have a higher stress job than predicted and also professional lives may