In 2008, average U.S household income was about $71,500, while the median -- or the point at which half of incomes are higher and half are lower -- was $52,000. The average skews higher than the median because of a few very high incomes, Deaton explained.
While people with household incomes of more than $75,000 probably won't feel an enduring happiness boost if they are able to earn more, losing substantial income would likely not be good for their emotional well being, the study suggested. As income dropped, respondents reported declining happiness and increased sadness and stress.
And,according to the study, poverty exacerbated the emotional impact of negative life events such as illness and divorce. Nor did the poor get as much of a happiness boost from weekends as those who were better-off, according to the researchers.
"Life is unfair for the poor in all sort of dimensions," Deaton said.
The U.S. National Institute of Mental Health has more information on anxiety and other mental health conditions.
SOURCES: Angus Deaton, Ph.D., professor, economics and international affairs, Princeton University, Princeton, N.J.; James Maddux, Ph.D., professor, psychology, George Mason University, Fairfax, Va.; PNAS. Sept. 6, 2010.
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