Sun exposure has its benefits, among them: enhancing passion in humans.

Researchers in Professor Carmit Levy’s Tel Aviv University (TAU) laboratory have found that exposure to ultraviolet radiation from sunlight increases levels of romantic passion in both genders. The radiation affects the regulation of the endocrine system responsible for the release of sexual hormones in humans.

The discovery was published as a cover story in the new issue of the scientific journal Cell Reports.

Professor Levy of the Department of Human Molecular Genetics and Biochemistry at TAU’s Sackler Faculty of Medicine says, “It has been known for many years now that ultraviolet radiation from sunlight increases testosterone levels in males, and we also know that sunlight plays a major role in both the behavioral and hormonal regulation of sexuality. However, the mechanism responsible for this regulation remained unknown. Our study enabled a better understanding of this mechanism.”

The discovery may lead to practical applications, such as UVB treatments for sexual hormone disorders. More research is required before this can be achieved, but according to Professor Levy, the breakthrough will also lead to further discoveries in basic science.

“Our findings open many scientific and philosophical questions,” Professor Levy says. “As humans, we have no fur, and our skin is directly exposed to sunlight. We are only beginning to understand what this exposure does to us, and the key roles it might play in various physiological and behavioral processes. It’s only the tip of the iceberg.”

The study culminated in a survey of 32 human subjects, who filled out validated questionnaires on behaviors of romantic passion and aggression. Treated with type b ultraviolet (UVB) phototherapy at the Tel Aviv Sourasky (Ichilov) and Assuta Medical Centers, both genders exhibited a rise in romantic passion, and males also noted an increase in levels of aggression.

Similar results were found when the subjects were asked to avoid sunlight for two days, and then tan themselves for approximately 25 minutes. Blood tests revealed that exposure to sunlight resulted in a higher release of hormones like testosterone compared to one day before exposure. A rise in testosterone in males during the summer was also found in analyses of data from the Clalit and Maccabi Health Services.

The study was led by PhD student Roma Parikh and Ashchar Sorek from Professor Levy’s laboratory. UVB phototherapy was administered to subjects at the Tel Aviv Sourasky (Ichilov) and Assuta Medical Centers.

Professor Carmit Levy is an associate professor in the Department of Human Molecular Genetics and Biochemistry at the Sackler Faculty of Medicine. She is a leading global researcher studying pivotal mechanisms in melanoma metastasis initiation, which opens horizons for new drugs to be used for the prevention of melanoma metastases. She is the 2019 recipient of the prestigious Young Investigator Award, recognizing her major contributions to the eld of melanoma research. The award is sponsored by the Melanoma Research Foundation, an international organization that centers on innovative melanoma research being done worldwide.  Read more about her work at https://carmitlevylab.com/.