The science of summer loving

Hot and heavy: Protein turns sun into sex drive, Israeli study finds

Cancer researchers in Tel Aviv accidentally discover same protein that protects from sun damage also gets animals, and seemingly humans, in the mood for love

Nathan Jeffay is The Times of Israel's health and science correspondent

A young couple in love, in the sun. (Aleksandar Karanov via iStock by Getty Images)
A young couple in love, in the sun. (Aleksandar Karanov via iStock by Getty Images)

Israeli researchers say that they have found the scientific reason behind summer loving, documenting a complex process that happens when sun hits the skin and boosts sex drive.

A team from Tel Aviv University is suggesting that the very same protein in the skin cells that protects DNA from being damaged by sunlight — p53 — causes hormonal, physiological and behavioral changes that trigger sex in animals and seemingly also get humans in the mood for love.

“Our lab studies skin cancer, and we accidentally started looking into how rays from the sun affect this protein and how in turn it impacts on sexual desire,” Prof. Carmit Levy, of the Department of Human Molecular Genetics and Biochemistry, told The Times of Israel. “There are many different proteins that we observed changing in the blood after exposure to sunlight that are related to passion.”

The findings have been peer-reviewed and published as a cover story in the scientific journal Cell Reports.

Levy said that her research could lead eventually to therapies that assess p53 levels and, based on where they stand, administer specific amounts of ultraviolet radiation type B (UVB), mimicking sunlight, to impact hormone levels and boost sex drive.

“Our findings suggest opportunities for treatment of sex-steroid-related dysfunctions,” her article states.

Illustrative image: A woman sunbathing. (bernardbodo via iStock by Getty Images)

Suggestions of a sun-sex connection are not new, and it has long been observed that sunlight stokes desire in men by increasing testosterone production, but the process that prompts such changes wasn’t well understood.

There were three stages in the new study, which was carried out by PhD students Roma Parikh and Ashchar Sorek. The first involved exposing mice to UVB rays. The research team reported “dramatic” results, with hormone levels rising significantly among females. The attraction between males and females increased, and both were more willing to engage in sexual intercourse.

“In female mice, UVB exposure increases hypothalamus-pituitary-gonadal axis hormone levels, resulting in larger ovaries,” the researchers wrote, adding that the number of days during which the mice were in heat rose from the norm. “UVB exposure also enhances the sexual responsiveness and attractiveness of females and male-female interactions.”

3D render of the p53 protein transcription factor bound to DNA. (Meletios Verras via iStock via Getty Images)

In the second stage, Levy and her colleagues wanted to check the accuracy of the hypothesis that the p53 hormone is responsible for the sexual changes. They removed p53 from the skin cells. Then, when they exposed the mice to UVB, it prompted no change in their sexual behavior.

In the study’s third stage, a small sample of humans were given UVB phototherapy at the Tel Aviv Sourasky (Ichilov) and Assuta medical centers.

When the 32 people were questioned, both genders described a rise in romantic passion. Then, they were told to avoid sunlight for two days and given a 25-minute sunbathing session. There were notable changes in their blood, including higher levels of hormones that get people in the mood for sex.

“We were surprised by our findings and feel they open up many more topics for research. They illustrate that the way our skin interacts with the environment arounds us impacts on our behavior in ways we are only starting to understand.”

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