Want to have the happiest summer ever? Make sure you grab your shades.
Aside from protecting your eyes from harmful UV rays, Italian researchers found that frowning caused by squinting in the sunlight actually has the power to make us feel angry*. Even involuntary facial expressions can trigger an emotional response, but researchers found that sunglass wearers were happier than those without, as they did not squint and therefore frown.
‘Sun-induced Frowning Fosters Aggressive Feelings’, Marzolia et al., Cognition & Emotion, 2013