WE KNEW IT. Now when someon says "why are you so grumpy?" you can just be like:
Studies show that by being in a bad mood, you're able to improve your memory, become more creative and be more motivated.
It has also been found that you can make better judgment calls about the people around you when you're in a wee grump. You're paying more attention to the situation meaning you'll be more aware if someones trying to decieve you.
But these effects are only the case if your bad mood comes and goes pretty quick, if you're 24/7 then that's not the same case. So hey if you're happy, sad, grumpy or mad (daaamn Dr Seuss aint'got nothing on us) then either way it's all good!