Regardless of whether money can buy happiness, being happy may actually make you more money down the road, new research finds.

People who express more positive emotions as teenagers and greater life satisfaction as young adults tend to have higher incomes by the time they're 29, according to a study published Monday by the US Proceedings of the National Academy of Sciences.

Maybe we've been asking the wrong question all along. It's not whether money brings happiness, but happiness brings money.

The difference was so great that when measuring life satisfaction on a 5-point scale, a 1-point jump at age 22 made a $2000 difference in income down the line. Between the gloomiest and the happiest brackets, that amounts to an $8000 earnings swing.

Drawing on data from the federally funded Add Health survey of teenagers, the researchers examined the profiles of more than 10,000 Americans at ages 16, 18 and 22 as well as their annual incomes at 29. They controlled for a number of factors known to contribute to financial success, including education level, IQ, height and self-esteem.