Researchers from the Cedars-Sinai Medical Center in Los Angeles say teaching heart patients how to meditate helped reduce the risk of future heart attacks.

Maura Paul-Labrador is lead author of the study that appeared in the Archives of Internal Medicine. She says there was already evidence that meditation lowers blood pressure, but researchers didn't know why. She says her new study shows it's because meditation affects the autonomic - or involuntary - nervous system, which, among other things, helps regulate heartbeat.

"We looked at what we called heart rate variability, which is a measure of autonomic nervous system." Paul-Labrador explains that heart rate varies from beat to beat. A healthy heart is one that has a wide range of speeds - from a slow heartbeat at rest, to a fast one for an active person. Hearts that change rate rapidly in response to changes in conditions, and then return to rest more quickly have good heart rate variability. Paul-Labrador says, "we were able to show that our meditation group improved their heart rate variability more than the active control group."

The researchers think people in the study lowered their blood pressure because of improvements in their autonomic nervous system. But they're still not sure exactly how it works. Some patients were even able to lower their doses of blood pressure medication.

In addition, Paul-Labrador says, "The meditation group was able to deal with their blood sugar better." Better control of insulin reduces their potential risk for diabetes. "You want your body to respond to lower levels of insulin, and so what we were able to find is that our meditation group was able to lower their insulin resistance compared to the active control group."

Paul-Labrador says people in the study meditated for 20 minutes, twice a day. She said the researchers had the subjects learn transcendental meditation because the practice is taught in a standardized way. She says other forms of meditation might also be effective, but they didn't study any other methods.