Researchers believe they can tell how vulnerable a person is to heart disease or a stroke by examining a single strand of their hair.
It is already known that elevated levels of stress raise the chances of a person suffering from cardiovascular problems.
Stress causes an increase in the cortisol hormones in the body and scientists at the Eramus Medical Centre in Rotterdam, Holland found that they can detect this by taking a one-inch sample of hair.
Lead author Dr Laura Manenschijn said: "Like high blood pressure or abdominal fat, the findings suggest elevated cortisol levels are an important signal that an individual is at risk of cardiovascular disease."
The study, which is published in The Journal of Clinical Endocrinology & Metabolism, looked at a group of 283 people aged between 65 and 85.
Study co-author Dr Elisabeth van Rossum said that additional studies need to be carried out to look at the long-term potential of using cortisol measurement as way of predicting cardiovascular disease.
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