clipped from www.livescience.com

And middle-age misery is not limited to the United States. In a separate study released in January, researchers in the United States and the UK looked at data on 2 million people from 80 nations and found most people are miserable in middle age. The probability of depression peaks around age 44, they found.

"Some people suffer more than others but in our data the average effect is large," said University of Warwick Economist Professor Andrew Oswald, who participated in the global study. "It happens to men and women, to single and married people, to rich and poor, and to those with and without children. Nobody knows why we see this consistency."

In the United States, Oswald and his colleagues found, unhappiness peaks at around age 40 for women and 50 years of age for men.

The 33 years of data revealed upticks in happiness when the nation flourished economically. For example, she found that 1995 was a very good year on the happiness scale.