Hot & heavy: Sunlight brings out romantic passion

TEL AVIV, Israel — Has the key to re-igniting romantic passion been shining down on us all along? Apparently, according to researchers from Tel Aviv University. Their study finds exposure to ultraviolet radiation via sunlight increases romantic passion in humans. Throw out the roses. Cancel the trip to the wine store. All you need for a romantic date is a little bit of sunlight.

Study authors exposed both men and women to UVB (ultraviolet radiation type B) within a controlled setting. The ensuing results were compelling. Both genders exhibited increased romantic passion.

Why does sunlight lead to love?

Researchers say UV light influences the regulation of the endocrine system, which is responsible for the release of sexual hormones.

“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,” says Prof. Carmit Levy from the Department of Human Molecular Genetics and Biochemistry at the Sackler Faculty of Medicine, in a media release.

To start researchers experimented with animal models, exposing animals to sun rays at wavelengths of 320-400 nanometers. It didn’t take long for females’ hormone levels to rise significantly, resulting in an enlargement of the ovaries and an extension of the mating season. Additionally, attraction between both males and females increased, and both genders were more willing to have sex.

Next, the same process was repeated, except a skin protein called p53 was removed from the animals. This protein is responsible for detecting DNA damage and activating pigmentation during sunlight exposure. This process acts as protection against sunlight’s adverse effects. Interestingly, removing p53 eliminated sunlight’s romantic effect on the animals.

What does tanning do to humans?

Finally, researchers tested 43 human subjects. Everyone filled out surveys asking about their usual levels of romantic passion and aggression. Then, after being exposed to sunlight, both genders showed an increase in romantic passion. Notably, male subjects also experienced an increase an aggression.

When participants were asked to avoid sunlight for two days, and then tan for 25 minutes, blood tests showed big upticks in hormones such as testosterone in comparison to one day before sun exposure. On a related note, men tend to have higher testosterone levels during the summer.

“The skin contains various mechanisms for dealing with radiation from sunlight, and one of these is the p53 protein. We must remember that exposure to UV is dangerous, and can damage the DNA, as in the case of skin cancer. At the same time, two built-in programs in the skin, activated following exposure to sunlight, are in place to protect against DNA damage: the DNA repair system and pigmentation, namely the suntan, based on degree of exposure. By activating both systems, the p53 protein regulates the level of DNA damage. In our study we found that the same system also activates the endocrine system of sexuality and potentially breeding,” Prof. Levy explains.

Besides just providing you with your next date idea (day at the beach, anyone?), study authors say these findings may one day lead to new UV-light-based treatments for various sexual hormone disorders.

“Our findings open many scientific and philosophical questions. As humans, we have no fur, and our skin is thus 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,” Prof. Levy concludes.

The study is published in Cell Reports.