Money can buy happiness, but only up to a point, according to the Easterlin paradox study. After people have taken care of their basic needs (plus a little extra), money doesn't really help at all. 

Dr. Thomas Gilovich, a psychology professor at Cornell University, and his team have been synthesizing research on the Easterlin paradox. He says that the best way to invest money into happiness is through experiences and adaptation is an enemy of happiness.

"We buy things to make us happy, and we succeed. But only for a while," Gilovich tells Fast Company. "New things are exciting to us at first, but then we adapt to them... Our experiences are a bigger part of ourselves than our material goods. You can really like your material stuff. You can even think that part of your identity is connected to those things, but nonetheless they remain separate from you. In contrast, your experiences really are part of you. We are the sum total of our experiences."

So, what is to be done? Gilovich believes that one thing is for employers to place a greater emphasis on paid vacations and for governments to invest in recreational space. After all, he asks, "As a society, shouldn't we be making experiences easier for people to have?"