Scientists have finally been able to prove what we've always known - long-term stress, from worries such as financial, marital and job problems, causes heart problems. Although all of us intuitively know it, scientists have been unable to prove a link between chronic stress and heart disease - until now. Scientists at the University if Western Ontario in Canada have come up with a hair analysis system that can detect stress over a long period, such as six months. Until now, serum, urine and saliva analysis could tell if the person was stressed only at the time the sample was taken, whereas heart problems are associated with chronic stress - when it is sustained over a lengthy time. As hair grows at around one centimetre a month, a hair sample that is six centimetres long gives a picture of stress levels - by measuring the levels of cortisol, the stress hormone - over a six-month period. To test the theory, the researchers took hair samples from 56 heart attack patients and 56 hospital patients without heart problems, and discovered that the heart patients had higher cortisol levels. (Source: Stress, 2010; doi: 10.3109/10253890.2010.511352).