Everyone around the water cooler knows that meditation reduces stress. But with the aid of advanced brainscanning technology, researchers are beginning to show that meditation directly affects the function and structure of the brain, changing it in ways that appear to increase attention span, sharpen focus and improve memory.

One recent study found evidence that the daily practice of meditation thickened the parts of the brain's cerebral cortex responsible for decision making, attention and memory. Sara Lazar, a research scientist at Massachusetts General Hospital, presented preliminary results last November that showed that the gray matter of 20 men and women who meditated for just 40 minutes a day was thicker than that of people who did not. Unlike in previous studies focusing on Buddhist monks, the subjects were Boston-area workers practicing a Western-style of meditation called mindfulness or insight meditation. "We showed for the first time that you don't have to do it all day for similar results," says Lazar. What's more, her research suggests that meditation may slow the natural thinning of that section of the cortex that occurs with age.

The forms of meditation Lazar and other scientists are studying involve focusing on an image or sound or on one's breathing. Though deceptively simple, the practice seems to exercise the parts of the brain that help us pay attention. "Attention is the key to learning, and meditation helps you voluntarily regulate it," says Richard Davidson, director of the Laboratory for Affective Neuroscience at the University of Wisconsin. Since 1992, he has collaborated with the Dalai Lama to study the brains of Tibetan monks, whom he calls "the Olympic athletes of meditation." Using caps with electrical sensors placed on the monks' heads, Davidson has picked up unusually powerful gamma waves that are better synchronized in the Tibetans than they are in novice meditators. Studies have linked this gamma-wave synchrony to increased awareness.

article on TIME by Liza Cullen