In US medical schools, one of the fastest growing areas of study is the healing power of... prayer.

Seventy-nine of the nation's 125 medical schools now offer courses on prayer and spirituality. A decade ago, only three medical schools offered such classes.

If doctors now believe that prayer and spirituality should be addressed during their training, can patients also benefit by learning more?

To find out about the recent surge of interest, Bottom Line/Health spoke to a leading expert in the healing power of prayer, Larry Dossey, MD...

Is there any scientific evidence to support the use of prayer in the prevention or treatment of disease? Researchers have conducted approximately 200 scientific studies on prayer and health. About two-thirds of these studies have shown positive results in patients with chest pain, heart attack and AIDS.

How was the research conducted? One of the most impressive studies is being conducted by researchers at Duke University Medical Center. The research, which will soon be published in the American Journal of Cardiology, shows how prayer affects heart patients.

When patients with severe chest pain were admitted for emergency treatment, they were given the option of participating in the study.

Of those who joined the study, half were randomly assigned to a group that was prayed for, while the other half was not prayed for.

Neither the patients nor their doctors knew who was being prayed for. Both groups received identical medical treatment.

The names of those in the prayed-for group were sent to prayer gatherings around the world, in every major religious tradition -- Buddhists in Tibet, Jews in Jerusalem, Hindus in India, Catholics and Protestants in the US and so on.

Those in the prayed-for group had half as many or, in some cases, no side effects or complications from invasive medical treatments, such as cardiac catheterization and angioplasty.

This study will surely make headlines -- and rightly so. It illustrates with exacting scientific methodology that prayer has a positive effect on recovery from serious illness.

Some people argue that the "placebo effect" is a factor -- that prayer may work because patients expect it to work. Has this point been considered in the research? That concern is best addressed by studies that look at the effect of prayer on nonhumans. Researchers have examined how prayer influences the healing of surgical wounds in mice and the growth rate of microbes in test tubes.

The positive results of these studies overcome the objections of skeptics, who argue that the effects of prayer are caused by the power of suggestion or positive thinking. These factors do not exist in nonhumans.

How does prayer work? Medical scientists, including some Nobel Prize winners, have advanced many theories that attempt to explain the scientific mechanics of "intercessionary" prayer -- when individuals are being prayed for by others rather than praying for themselves.

My favorite example is that put forth by David Chalmers, PhD, a cognitive scientist at the University of Arizona in Tucson.

In a paper published in 1995 in Scientific American, Chalmers asserts that there is a large body of scientific evidence suggesting that consciousness is a fundamental element of the universe -- like matter and energy. It's a medium that is neither made by the brain nor dependent on the brain for its existence.

If you accept that consciousness exists in this way, you can see how intercessionary prayer could affect the health of a person being prayed for.

I don't know if this hypothesis will prevail, but it shows the approach that distinguished scientists are taking in their attempts to explain how prayer works.

Is a belief in God -- or some other higher being -- required in order to benefit from prayer? Scientific studies on nonhumans show that you don't have to have faith or belief for intercessionary prayer to work for you.

If you are praying for someone else, however, double-blind studies show that the effectiveness of prayer is influenced by empathy, love and compassion. If you believe prayer is a sham, it's unlikely you'll muster the requisite feelings that seem to make prayer work.

The same principle applies when praying for yourself (petitionary prayer).

You must first accept the efficacy of prayer -- regardless of whether you think it works because of a supreme being or simply as a result of caring and empathy.

What is the best prayer method? The crucial factor is not what you do, but your attitude -- genuine concern is a fundamental element in the success of prayer. Scientific studies show that it's irrelevant to whom you are praying.

What is the best way to start praying? To begin praying, choose a practice that matches your temperament...

Extroverted, results-oriented people often pray for specific outcomes, such as make my heart disease better... or regulate my blood sugar.

Introverted, inner-directed people are often reluctant to dictate an outcome. Instead, they are typically more comfortable with an accepting approach, such as let thy will be done... or may the best thing happen.

Is there an ideal time or place for prayer? Concentration contributes to effective prayer. If you're thinking about what to make for dinner, you're not praying.

That's why many people who pray set aside a time of day when they won't be disturbed. They also tend to pray in a quiet place, such as a church or synagogue, a special corner of the house or in a park.

While these rituals aren't necessary for effective prayer, they may benefit your own health. Getting quiet and praying for yourself or another person is a highly effective way to induce healthy physiological changes that scientists refer to as the "relaxation response." This occurs when blood pressure falls, heart rate drops and the body requires less oxygen.