2. Giving is good for our health. A wide range of research has linked different forms of generosity to better health, even among the sick and elderly. In his book Why Good Things Happen to Good People, Stephen Post, a professor of preventative medicine at Stony Brook University, reports that giving to others has been shown to increase health benefits in people with chronic illness, including HIV and multiple sclerosis.

A 1999 study led by Doug Oman of the University of California, Berkeley, found that elderly people who volunteered for two or more organizations were 44 percent less likely to die over a five-year period than were non-volunteers, even after controlling for their age, exercise habits, general health, and negative health habits like smoking. Stephanie Brown of the University of Michigan saw similar results in a 2003 study on elderly couples. She and her colleagues found that those individuals who provided practical help to friends, relatives, or neighbors, or gave emotional support to their spouses, had a lower risk of dying over a five-year period than those who didn't. Interestingly, receiving help wasn't linked to a reduced death risk.

Researchers suggest that one reason giving may improve physical health and longevity is that it helps decrease stress, which is associated with a variety of health problems. In a 2006 study by Rachel Piferi of Johns Hopkins University and Kathleen Lawler of the University of Tennessee, people who provided social support to others had lower blood pressure than participants who didn't, suggesting a direct physiological benefit to those who give of themselves.

3. Giving promotes cooperation and social connection. When you give, you're more likely to get back: Several studies, including work by sociologists Brent Simpson and Robb Willer, have suggested that when you give to others, your generosity is likely to be rewarded by others down the line sometimes by the person you gave to, sometimes by someone else.

These exchanges promote a sense of trust and cooperation that strengthens our ties to others and research has shown that having positive social interactions is central to good mental and physical health. As researcher John Cacioppo writes in his book Loneliness: Human Nature and the Need for Social Connection, "The more extensive the reciprocal altruism born of social connection . . . the greater the advance toward health, wealth, and happiness."

What's more, when we give to others, we don't only make them feel closer to us; we also feel closer to them. "Being kind and generous leads you to perceive others more positively and more charitably," writes Lyubomirsky in her book The How of Happiness, and this "fosters a heightened sense of interdependence and cooperation in your social community."


4. Giving evokes gratitude. Whether you're on the giving or receiving end of a gift, that gift can elicit feelings of gratitude it can be a way of expressing gratitude or instilling gratitude in the recipient. And research has found that gratitude is integral to happiness, health, and social bonds.

Robert Emmons and Michael McCullough, co-directors of the Research Project on Gratitude and Thankfulness, found that teaching college students to "count their blessings" and cultivate gratitude caused them to exercise more, be more optimistic, and feel better about their lives overall. A recent study led by Nathaniel Lambert at Florida State University found that expressing gratitude to a close friend or romantic partner strengthens our sense of connection to that person.

Barbara Fredrickson, a pioneering happiness researcher, suggests that cultivating gratitude in everyday life is one of the keys to increasing personal happiness. "When you express your gratitude in words or actions, you not only boost your own positivity but [other people's] as well, she writes in her book Positivity. "And in the process you reinforce their kindness and strengthen your bond to one another."


5. Giving is contagious. When we give, we don't only help the immediate recipient of our gift. We also spur a ripple effect of generosity through our community.

A study by James Fowler of the University of California, San Diego, and Nicholas Christakis of Harvard, published in the Proceedings of the National Academy of Science, shows that when one person behaves generously, it inspires observers to behave generously later, toward different people. In fact, the researchers found that altruism could spread by three degrees from person to person to person to person. "As a result," they write, "each person in a network can influence dozens or even hundreds of people, some of whom [they do] not know and [have] not met."

Giving has also been linked to the release of oxytocin, a hormone (also released during sex and breast feeding) that induces feelings of warmth, euphoria, and connection to others. In laboratory studies, Paul Zak, the director of the Center for Neuroeconomics Studies at Claremont Graduate University, has found that a dose of oxytocin will cause people to give more generously and to feel more empathy towards others, with "symptoms" lasting up to two hours. And those people on an "oxytocin high" can potentially jumpstart a "virtuous circle, where one person's generous behavior triggers another's," says Zak.

So whether you buy gifts, volunteer your time, or donate money to charity this holiday season, your giving is much more than just a year-end chore. It may help you build stronger social connections and even jumpstart a cascade of generosity through your community. And don't be surprised if you find yourself benefiting from a big dose of happiness in the process.