From Science of Us:
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.
Two other detailed reasons are also given.
(Score: 2, Interesting) by Jesus_666 on Wednesday July 09 2014, @07:16PM
WRT your comment on lighting: The presence of sunglasses is orthogonal to ambient lighting conditions. There are bright pictures of people without sunglasses and there are dim pictures of people wearing them. Likewise, even basement dwellers can put on sunglasses and, amazingly enough, runway models often don't wear them on the runway. The effect sunglasses have on a person's appearance are irrespective of lighting conditions.
WRT your activity comment: That may be true; there certainly is an association of sunglasses with an active, fun lifestyle. Then again, skiers tend to wear ski goggles, which are certainly connected to an active, fun lifestyle but aren't terribly attractive if worn with anything but skiing gear. Imagine, for instance, how silly The Matrix would've looked with everyone in trenchcoats and ski goggles. While the association with fun activities may be relevant it's certainly not everything. It's perfectly compatible with the findings from TFA, though, so it may be a contributing factor.