It turns out, giving thanks is good for your health.

A growing body of research suggests that maintaining an attitude of gratitude can improve psychological, emotional and physical well-being. Adults who frequently feel grateful have more energy, more optimism, more social connections and more happiness than those who do not, according to studies conducted over the past decade. They're also less likely to be depressed, envious, greedy or alcoholics. They earn more money, sleep more soundly, exercise more regularly and have greater resistance to viral infections.

Now, researchers are finding that gratitude brings similar benefits in children and adolescents. Kids who feel and act grateful tend to be less materialistic, get better grades, set higher goals, complain of fewer headaches and stomach aches and feel more satisfied with their friends, families and schools than those who don't, studies show.

"A lot of these findings are things we learned in kindergarten or our grandmothers told us, but we now have scientific evidence to prove them," says Jeffrey J. Froh, an assistant professor of psychology at Hofstra University in Hempstead, N.Y., who has conducted much of the research with children.

"The key is not to leave it on the Thanksgiving table," says Robert Emmons, a professor of psychology at the University of California-Davis and a pioneer in gratitude research. And, he notes, "with the realization that one has benefited comes the awareness of the need to reciprocate."

Philosophers as far back as the ancient Greeks and Romans cited gratitude as an indispensable human virtue, but social scientists are just beginning to study how it develops and the effects it can have.

The research is part of the "positive psychology" movement, which focuses on developing strengths rather than alleviating disorders. Cultivating gratitude is also a form of cognitive-behavioral therapy, which holds that changing peoples' thought patterns can dramatically affect their moods.

It's possible, of course, to over-do expressions of gratitude, particularly if you try to show it with a gift. "Thanking someone in such a way that is disproportionate to the relationship—say, a student giving her teacher an iPod—will create resentment, guilt, anger and a sense of obligation," says Froh.

Gratitude can also be misused to exert control over the receiver and enforce loyalty. Froh says you can avoid this by being empathic toward the person you are thanking—and by honestly assessing your motivations.

In an upcoming paper in the Journal of Happiness Studies, Froh and colleagues surveyed 1,035 high-school students and found that the most grateful had more friends and higher GPAs, while the most materialistic had lower grades, higher levels of envy and less satisfaction with life. 

"One of the best cures for materialism is to make somebody grateful for what they have," Froh says.

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