There is a saying, "An apple a day keeps the doctor away." Although eating properly is important, being kind to others is also good tor your health. Studies show that people who perform kind acts are more relaxed, happier, and healthier than other people. In one study at Arizona State University researchers, found that many volunteers experienced a sudden feeling of joy, followed by a long period of calm, after performing a kind act.  This feeling, called "a help's high" may actually help reduce stress   as the body releases   naturally painkillers. Stress can cause' serious health problems, and heart depression, and .sleeping problems. However, the study found that volunteers had fewer *stress-related health problems when they did helpful things for other people. The study also found that people who did nice things for others felt better about themselves as well. They had higher self-esteem  , and were' happier. Many believe this is because volunteers spend more of their time with other people. People who are more outgoing are often healthier. Another study at the University of Michigan's Survey Research Center confirmed the health benefits of volunteering. A ten-year study showed that people who volunteered live longer than those who didn't. Although you shouldn't need a reason to be helpful, it is nice to know that kindness may help you live longer. The study found that people who help others can have   _  .
sleeping problems and stress less natural painkillers overeating and depression problems fewer health problems