Scientists say that what you breathe out could also be used to understand whether or not you are under stress. Deep breathing is recommended for stress busting.
Paul Thomas, professor at Imperial College London, who led the study, said: "If we can measure stress objectively in a non-invasive way, then it may benefit patients and vulnerable people in long-term care who find it difficult to disclose stress responses to their carers, such as those suffering from Alzheimer's."
Six markers in the breath, identified in group of young male and female adults, could be developed as a quick, simple and non-invasive test for measuring stress, added Thomas, the Journal of Breath Research reports.
Two compounds in the breath - 2-methyl, pentadecane and indole - increased, following the stress exercise which, if confirmed, could form the basis of a rapid test. A further four compounds were shown to decrease with stress, which could be due to changes in breathing patterns.
In the first study, volunteers were asked to sit comfortably and listen to non-stressful music; in the second, they were asked to perform a common arithmetic test, designed to induce stress, according to an Imperial statement.
A breath test was taken before and after each session, while heart-rates and blood pressures were recorded throughout. The breath samples were examined using a technique known as gas chromatography-mass spectrometry, and then statistically analysed and compared to a library of compounds.
Breath profiling has become an attractive diagnostic method for clinicians, and recently, researchers have found biomarkers associated with tuberculosis, multiple cancers, pulmonary disease and asthma.
"It is possible that stress markers in the breath could mask or confound other key compounds that are used to diagnose a certain disease or condition, so it is important that these are accounted for," said Thomas.