The happier you are, the better, right? Not necessarily. Studies show there is a darker side to feeling good and the pursuit of happiness can sometimes make you … well, less happy. Too much cheerfulness can make you gullible, selfish, less successful – and that’s only the tip of the iceberg.

Happiness can protect us from stroke and the common cold, make us more resistant to pain and even prolong our lives. Yet it’s important to experience positive moods in moderation, warns June Gruber, a professor of psychology at Yale University.

via Huge doses of happiness can have serious side-effects.