Anyone who has ever had the smell of phenol in their nose will not associate it with erotic feelings.

The presence of traces of this compound in a man's breath indicates sexual arousal: This is one of the results of a study by the Max Planck Institute for Chemistry in Mainz.

In experiments at the University of Porto's "Sex Lab", the researchers found that sexually stimulated people exhale a typical cocktail of molecules.

The scientists believe the discovery may help diagnose sexual dysfunction.

Sasha Zoske

Sheet maker in the Rhein-Main-Zeitung.

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The team led by the psychologist Pedro Nobre and the atmospheric researcher Jonathan Williams showed twelve men and twelve women different ten-minute film clips in random order in the laboratory: a nature documentary, a horror film, a soccer game and an erotic film.

The air breathed by the test subjects was continuously analyzed for more than 100 organic compounds.

The researchers also measured sexual arousal based on the temperature of the genitals, among other things.

happiness hormone in the air

When the sex film was viewed, the composition of the exhaled air changed noticeably: The concentration of carbon dioxide and isoprene fell, which according to the chemist Nijing Wang could be due to the fact that the genitals were supplied with more blood, while the muscles and lungs were less.

Instead, other substances stood out: “We found phenol, cresol and indole in men,” reports Wang.

"These seem to be typical indicators of sexual arousal." The researcher explains the occurrence of these compounds by saying that they are breakdown products of tryptophan and tyrosine.

The body uses these amino acids to produce the neurotransmitters serotonin or dopamine and noradrenaline - messenger substances that cause euphoria during sexual arousal.

In principle, however, the results of the breath analysis were clearer in men than in women, says postdoc Giovanni Pugliese.

This could also be related to the fact that some women were not particularly aroused by the erotic film.

"In order to increase the overall significance, we would like to repeat the study with a larger number of subjects," says Pugliese.

The researchers also want to test whether people in other situations also send fleeting signals that the other person can perceive - for example when talking, kissing or hugging.