Arousal is reflected in the breath

Researchers are on the trail of the signature of pleasure in the breath. © Gpointstudio/iStock

When you are sexually aroused, something happens in the body – and this is evidently also noticeable in the air a person breathes: Feelings of pleasure change the concentrations of certain volatile substances in a characteristic way, according to an experimental study. The researchers say that this comparatively simple means of detection could benefit research into sexual dysfunction.

When air flows through the respiratory tract and lungs, it absorbs a complex load: In addition to the carbon dioxide from our metabolism, the tissue also releases many volatile substances of different origins into the air we breathe. Previous investigations have already shown that certain processes in the body cause a characteristic signature that can be analytically proven. The scientists led by Jonathan Williams from the Max Planck Institute for Chemistry in Mainz (MPI-C) are dealing with this research topic. They have already been able to show that emotional states are also reflected in the chemical characteristics of the air we breathe: by analyzing the air in a cinema hall, they were able to identify characteristic volatile substances that viewers exude during exciting scenes.

In their current study, together with colleagues from Portugal and the Netherlands, they have now turned their attention to a special form of tension: “With the study on sexual arousal, we wanted to test whether other strong emotions also leave a trace in the breath,” says Williams. It stood to reason that the physical and mental responses associated with feelings of pleasure also produce specific signatures. “However, to characterize the chemical signals, we performed tests under controlled conditions and not under the complex conditions in a cinema,” says Williams. Twelve men and twelve women with an average age of 27 agreed to the spicy experiments. According to their personal information, they were heterosexual, sexually active and healthy.

Breath tests in the “SexLab”

During the experiments, they sat in a test room in the Research Laboratory on Human Sexuality, or SexLab for short, at the University of Porto. There, various ten-minute film clips were presented to them in random order on a monitor: These were pieces from nature travel documentaries, horror films, soccer games – and erotic films. Meanwhile, the breath of the study participants was continuously recorded via a mask and analyzed for the content of over one hundred volatile organic compounds. At the same time, the researchers examined the extent to which the erotic film could trigger sexual arousal in the subjects. One indication of this was provided, among other things, by infrared images of the genitals, which reflected increased blood flow. Apparently, the researchers were lucky and at least some of the subjects felt pleasure even in the comparatively non-erotic research atmosphere.

As it turned out, at the start of the erotic film, the amount of various volatile organic compounds in the air they breathed increased rapidly – other compounds, however, decreased: the test subjects exhaled less isoprene and carbon dioxide, but the concentration of degradation products of certain neurotransmitters increased. “The fact that the concentration of CO2 and isoprene in the breath fell could be due to the fact that the genitals were supplied with more blood, while the muscles and lungs were less supplied with blood,” explains first author Nijing Wang from the MPI-C. “In men we found phenol, cresol and indole. These seem to be typical indicators of sexual arousal.”

A whiff of lust is in the air

As the researchers explain, it is known that these substances are breakdown products of prominent substances: they are formed when the amino acids tryptophan, a precursor of the neurotransmitter serotonin, and tyrosine, from which our body forms dopamine and norepinephrine, are broken down. In turn, these messenger substances are known to play an important role in erotic feelings and are formed quickly. Among other things, they bring people into the typical euphoric state of mind when they are sexually aroused, the scientists explain. They were even able to detect the happiness hormone dopamine directly in the breath of one of the excited subjects.

On average, however, the women were much less excited by the erotic films than the men, the tests showed. “The results of the breath analysis in the men were also clearer than in the women,” says co-author Giovanni Pugliese from the MPI-C. The researchers did not observe the same increase in volatile substances in women as in men. Therefore, according to them, there is now a need for further research in order to better explore the effects: “In order to increase the overall significance, we would like to repeat the study with a larger number of test persons,” says Pugliese. The team also wants to study how people produce specific volatile chemical signatures when they talk, kiss or hug. This also raises the question of whether we can perceive these signals consciously or unconsciously.

As the researchers conclude, the insights could benefit the study of human sexuality: “Being able to non-invasively determine a person’s sexual arousal via breath would represent a major advance for sex studies,” says co-author Pedro Nobre. Until now, such studies have been made more difficult by the fact that sensors have to be attached directly to the genital area of ​​the test person. “Breath analysis could facilitate the assessment of sexual arousal and thus help in the investigation of sexual dysfunctions,” says the sex researcher.

Source: Max Planck Institute for Chemistry, specialist article: Scientific Reports, doi: 10.1038/s41598-022-10325-6

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