Here's another excuse for people to wear their sunglasses.
A new study finds people who don't wear them are unhappier than those who do. The Smithsonian Magazine surveyed people walking on a boardwalk with and without sunglasses. They found that people who weren't protecting their eyes had greater feelings of anger and aggression.
Researchers think it is because if people are squinting in the sun, they are probably frowning as well. That can make someone feel angry even if they are not.