In the Himalayas, Buddhist monks perform an amazing feat: Dressed only in light cotton robes, they go out in zero-degree-Fahrenheit temperatures, sit motionless and meditate for eight hours straight, without shivering, without frostbite, without showing any signs of cold.

The fact that the monks can accomplish this task has been documented by western researchers, but exactly how the monks do it is still a mystery.

The leading scientific theory is that by meditating the monks tap into a physical process called nonshivering thermogenesis (which has been documented in mammals, particularly those who hibernate). Nonshivering thermogenesis enables the body to burn "brown fat" and thereby generate very large amounts of heat.

"We hypothesize," suggests Dr. Herbert Benson, a Harvard researcher who has studied the monks, "that they have learned to do this through the use of generally unknown powers of the mind." :: :: ::

Can the mind be tapped for physical potential? Is there such a thing as mind over matter that might help combat illness? Are there ways to expand what the mind can do?

Probing the mind-body connection is the focus of "Your Maximum Mind," the latest book by Benson, a physician who heads the Behavioral Medicine Section at New England Deaconess Hospital in Boston.

Benson, who also teaches at Harvard Medical School, is best known for describing the relaxation response -- the physical change in the body, characterized by reduced heart rate, slower breathing and decreased blood pressure. Unlike biofeedback -- which a National Research Council committee found last week to be ineffective in controlling stress -- studies show that the relaxation response can be helpful in reducing stress, controlling high blood pressure and combating chronic pain.

In "Your Maximum Mind," Benson takes his theory another step and marries physiology with the power of faith. His premise: By combining the relaxation response with meditation or prayer, it is possible to make quantum changes in the mind -- to, as Benson puts it, "rewire your brain" and, therefore, reap physical rewards with better health.

It may sound a bit far-fetched, but Benson's work is part of a new and rapidly growing scientific field called psychoneuroimmunology (PNI). PNI is drawing researchers from psychology, immunology, neurology and other fields to investigate how the mind and the body interact. Their findings are injecting a new vigor into American medicine, one that has implications for such wide-ranging medical problems from acquired immune deficiency syndrome (AIDS) to warts.

No one, including Benson, proposes that PNI take the place of conventional medicine. Rather, the discoveries of PNI are considered important additions to the practice of mainstream medicine.

Numerous studies show that there are many connections between the brain and the immune system and between the brain and the endocrine system. For example, at Ohio State University, psychologist Janice Kiecolt-Glaser and her immunologist husband Dr. Ronald Glaser have shown that the relaxation response can enhance the immune systems of healthy, elderly men and women.

Benson and his colleagues have shown that brain changes occur during the relaxation response, which enable the left and right hemispheres of the brain to interact more. They have also found that there are alterations in brain wave frequencies, with an "increased coherence" between alpha and theta waves, produced by the two sides of the brain during the relaxation response, and suggesting that the two hemispheres are again more in "sync" with each other.

Just as belief or attitude can cause pain (thinking something is going to hurt makes it hurt even more), "our mental processes can also reduce or eliminate painful sensations," Benson writes.

"Your brain-cell connections can remember a headache and can also remember feelings of well-being," he says. "Furthermore, they can remember the relief brought about naturally or by the taking of medication -- and this particular capacity offers great potential for medical treatment."Tapping into these processes could also help explain the mystery of the placebo effect -- the well-documented, powerful effect of "sugar pills" in "curing" certain ailments -- because people believed that they contained medicine.

Coming from a less well-respected physician, or one with fewer credentials, "Your Maximum Mind" would just be the latest bean-sprouts-and-granola tome. But Benson is careful to cite published scientific studies to support his theories. And the extensive bibliography includes papers published in such highly regarded journals as Science, the New England Journal of Medicine, the Journal of American Psychiatry and the American Journal of Public Health.

"Your Maximum Mind" is a readable book, generally written in a clear, concise style. (Benson teamed with the writer William Proctor, who also was his co-author for an earlier book, "Beyond the Relaxation Response.")

Occasionally, the message gets a bit heavy-handed, such as when Benson suggests finding a "maximum mind guide" -- actually a mental health professional or a member of the clergy. But over all, "Your Maximum Mind" is free of preachy overtones.

The goal of "Your Maximum Mind" is to teach readers how to realize greater mental awareness, which in turn could be helpful in promoting better health. Few could argue with the merits of that.