The number one killer in this world is anger. On the death certificate it gets translated as Heart disease or cancer. Earlier doctors believed that there were physical factors that cause heart diseases, like aging, high level of cholesterol in the blood, high BP, diabetes, family history, smoking, obesity and insufficient exercise. Research on psychosomatic medicine shows that people who harbor grudges or display hostility are more than twice as likely have premature heart attacks. As early as 1939 Franz Alexander suggested that people who get high BP often struggle against their feelings of anger.
Anger is an emotional state ranging from irritation and annoyance to fury and rage.
If you express anger by acting it out, it is overt expression. It is seen that people in a dominating position express their anger directly, like mother to child, husband to wife, boss to employee and so on. Overt expression of anger results in High BP, heart attacks, etc. Covert expression of anger is when people have learnt that it is wrong to express anger so they direct it into themselves. These are the silent sufferers.