You know you’re at least a little curious. And so was Vanessa Brown, a senior lecturer of art and design at Nottingham Trent University in the U.K. Her research focuses on the meaning we assign to commonplace, everyday objects, and in an academic book that’s coming out early next year, she explores the cultural and psychological relationship between sunglasses and our modern idea of “cool.” In an email to Science of Us, Brown explained what her research has uncovered about why most of us look better in shades.

Because they really do make your misshapen face look better. Put on a pair of sunglasses, and voilà – instant symmetry! The dark lenses cover up any asymmetrical oddities around your eyes, and research on facial attractiveness shows a clear link between symmetry and our perception of beauty.

As an added bonus, Brown pointed out, sunglasses provide a kind of scaffolding effect, imposing the appearance of an external, extra-chiseled bone structure on top of your relatively softer-featured face.

Because mystery. Many of the snap judgments we form about people come from looking them in the eyes; shade yours, and you’re instantly a more intriguing presence. “The eyes are such a tremendous source of information — and vulnerability — for the human being,” Brown explained. Eye contact helps us form judgments about someone’s intelligence, confidence, andsincerity, and sunglasses keep us literally in the dark about forming those perceptions about a person. And it works both ways, because the wearer of the sunglasses feels more inscrutable, too. One recent study showed that people who wore sunglasses acted more selfishly and dishonestly than those wearing eyeglasses, which, the researchers argue, suggests that shades delude us into feeling more anonymous, or unknown.

It's colloquial wisdom that an air of mystery increases sexual desire, and research bears that notion out. Think of the common “the thrill is gone” complaint that accompanies the long-term relationship, for one. And one recent study showed that women who were uncertain of a man's feelings toward them ended up reporting more attraction to those men. It's essentially the plot of many a rom-com: We're drawn to the people we can't quite figure out.

Because of their historical link with edginess and glamour. We take their ubiquity for granted today, but sunglasses are a relatively modern everyday accessory, Brown said. Sales started to pick up in the 1920s, but they didn’t become commonplace until about two decades after that. The way sunglasses were most often used prior to their commercialization helps explain some of their inherent coolness, Brown said, because in their early days sunglasses were primarily used during risky water and snow sports, and were also associated with new technologies like airplane travel, which made them seem “daring and thoroughly modern.”

Soon after that, Hollywood stars of the 1950s and 1960s started wearing sunglasses to defend themselves from being recognized by the public or harassed by paparazzi, whose flashbulbs would often explode violently, sometimes literally in their faces, Brown said. But regardless of practicality, movie stars’ adoption of the accessory cemented the link between sunglasses and glamour.

Also – and this is more from my own personal research than Brown’s — hang-overs. They’re really great for hiding hang-overs.