As far as hostility is concerned, it is not clear which type is bad. Is it the overt hostility (all lawyers watch out— you may be at higher risk of coronary disease!) or is it the repressive type (the tendency not to express your emotions when angry)? There are contradictory studies, which favour the different viewpoints. One fascinating study seems to give a better picture. In that study, healthy volunteers were shown a film clip that evokes some strong emotions (like a surgical procedure with blood and all the internals).
The volunteers showed strong signs of sympathetic nervous system activation (stress response). Another set of volunteers was shown the same clip but they were instructed beforehand not to display their emotions. After the film, this group had a higher stress response than the group who were not prevented from expressing their emotions. Thus, repression tends to exaggerate the intensity of the stress response.
Irrespective of which type of hostility is more harmful, the interesting question is why should hostility cause a greater risk of coronary disease? Some interesting studies will help us find the answer. First, a group of hostile and non-hostile people was given some math problems to solve (non-social stressor). Nothing exciting and both groups had roughly the same stress response.
Now, throw in some social provocation (like being repeatedly interrupted during the test, loud noises in the background) and every time, the hostile people had a high stress response. They were dumping the hormones epinephrine, norepinephrine in their bloodstream and showed elevated blood pressure.
A number of similar experiments have been conducted with different settings and different social stressors. They all point to the higher stress response in hostile people. Subjectively, we can say that hostile people get angry over incidents that most of us would ignore or find mildly provocative. For the hostile (anxious) people, life is full of menacing situations that demand constant vigilance and a particularly hostile response. They probably go through life viewing the world as full of provocations that everyone else does not find bothersome.
At the beginning of the chapter, I pointed out an important caveat when talking about personality types—that having a specific personality type increases your risk of coronary disease but that you can change your personality and reduce your risk. If such people reduce their hostility through therapy or their own efforts, their risk of heart disease goes down. Put simply, the hostile people are not being nice to those around them. In non-scientific terms, they should strive to be nicer and bring a smile to the faces of those around them. It will have a positive impact on their own lives.