Esther Sternberg needed a break. After spending months as a long-distance caregiver for her terminally ill mother, she developed inflammatory arthritis. The irony wasn't lost on Sternberg, a research scientist at the National Institutes of Health who studies the link between stress and disease.

In 1997, shortly after Sternberg's mother died, neighbors invited her to visit them at their cottage in Crete. "I was in this beautiful spot, an isolated village on the south coast of the island," she says of the trip. "I swam in a wonderful calm cove and started walking more every day. I ate a healthy Mediterranean diet and had lots of social support from the many grandmothers in town who took care of me." Sternberg says she'd climb the hill to the Temple of Asclepios (perhaps not so coincidentally the Greek god of healing) and relax while looking out at the bougainvillea, the white stucco houses, and the sea. "I realized that I wasn't going to let my body heal unless I let go and built into my life the kinds of things I was doing on this trip. The experience convinced me to change my lifestyle."

When she got back to her home in Bethesda, Maryland, Sternberg continued to swim and take time out to "reflect and be quiet," and her arthritis receded. "My story may not be scientific," she says, "but it's a testimonial to the potential beneficial effects of vacation on health." And on work: A PBS special based on her books and research, The Science of Healing with Dr. Esther Sternberg, airs later this fall.

Common sense suggests that vacations are good for you, but science is now proving what we've known all along. In 1992, a follow-up to the massive Framingham Heart Study showed that participants who took the fewest holidays were most likely to suffer a heart attack. A study by the State University of New York, Oswego, published in 2000, tracked male patients at risk of heart disease over a 16-year period. "The results," says lead researcher Brooks Gump, "show an association between taking an annual vacation and a reduced risk of heart attack and death." In Gump's study, those who took fewer holidays were 30 percent more likely to die of a heart attack.

Vacation time may even stave off old age. "The ends of chromosomes are like the plastic ends of shoelaces," says Sternberg, crediting the work of Elissa Epel, a researcher at the University of California, San Francisco. "As you age, these ends fall off, the shoelaces unravel, and the chromosomes shorten. If you are chronically stressed, the rate at which this happens speeds up, so people can have chromosomes that are 10 to 17 years shorter than their biological age." Stress has also been shown to ignite or exacerbate ailments ranging from headaches to heart disease, colds to cancer. "To the extent that the kinds of things you do on holiday have been shown to reverse the negative effects of stress," Sternberg says, "we can conclude that vacations can only help."

Yet despite the clear benefits of getting away, Americans take less time off than citizens of any other country in the industrialized world: Employers in Finland and France, for instance, are required to give employees six weeks off a year, while the United States has no mandatory minimum vacation time and a third of Americans don't use all of the days that they are allotted.

Vacations, of course, can range from a do-nothing week on the beach to a cultural and shopping tour of a European capital to a high-adrenaline adventure in the Amazon. But the good news, according to experts, is that almost any type of holiday can benefit health to some degree because people tend to be happier and less stressed when they anticipate them and happier still—and sleeping longer and better—while they're away. Of course, for travel to have a positive impact, we need to make smart choices: a week in Paris bingeing on foie gras and cognac may not have the desired rejuvenating effect.

"People often look at vacations as a time to drink too much and eat unhealthy foods," says best-selling author Dr. Andrew Weil. "If we begin to consider the possibility that vacations can be health-promoting, that's a very good thing." Dr. Michael Irwin, director of UCLA's Cousins Center for Psychoneuro­immunology (the study of the interaction between the mind and the nervous and immune systems), agrees. "We get stuck in ruts. Vacations can help us develop healthy patterns to carry into our lives," he says.