Being fiery and expressing negative emotions can add two years to your life, say researchers.
In contrast, the British characteristic of self-restraint can have serious repercussions for physical and mental well-being, they said.
Researchers at the University of Jena in Germany assessed more than 6,000 patients and found that those who internalised their anxiety suffered from a raised pulse, the Daily Mail reported.
In the long run this results in high blood pressure and an increased chance of developing a wide range of illnesses, from coronary heart disease to cancer and kidney damage.
The research by Marcus Mund and Kristin Mitte identified a group of so-called 'repressors' who were particularly at risk.
According to Mund, these people are distinguished by the way that they attempt to conceal outward signs of fear, and also by their defensive behaviour.
They avoid risks and always seek a high level of control over themselves and their surroundings, he said.
When exposed to a stressful task these people, Mund said, exhibit a higher heart rate and pulse ratio than non-repressors and show other objective signs of stress and anxiety.
Although they might be at a higher risk of developing certain illnesses, recovery from a range of conditions appears to be faster among repressors.
Because of their need for control, repressors are very disciplined and more motivated to adapt their lifestyles, Mund said.
The results have been published in the journal Health Psychologies.