I tend to wear dark, dull colors a lot and — now that I think about it — when I do I tend to be a little more mopey than I would otherwise feel. I’m not the only one. According to a 2010 study out of the journal BMC Medical Research Methodology, bright colors go hand-in-hand with happiness. This is especially true of yellow, the study found, as happier people favor that color. Oppositely, gray was most closely associated with anxiety and depression in the study.