Levels of cortisol have previously been measured in blood, urine and saliva, but these measurements only provide a snapshot of stress at the moment.
Hair cortisol can provide a longer-term assessment of stress.
In a new study, hair cortisol levels were actually a more important predictor of heart attack risk than other known heart disease risk factors such as high blood pressure, smoking and cholesterol.
The findings appear online in the journal Stress.
