According to the Washington Post  A professor at Yale University studied happiness and warns that just like everthing it is best in moderation. 

She compares happiness to food: Although necessary and beneficial, too much food can cause problems; likewise, happiness can lead to bad outcomes.

“Research indicates that very high levels of positive feelings predict risk-taking behaviors, excess alcohol and drug consumption, binge eating, and may lead us to neglect threats,” she says.

So what do you think can you be too happy?