In the late 1960s a cardiologist at Harvard named Herbert Benson became interested in a strange thing he kept noticing in his patients. The ones who practiced transcendental meditation had measurably lower blood pressure than the ones who did not. He measured them, and measured them again, and eventually concluded he was looking at a coherent physiological response distinct from sleep and distinct from ordinary rest. He gave it a name: the relaxation response.

This was 1975. Benson went on to study it for the next forty years.

What he found, and what hundreds of researchers have replicated since, is that a particular cluster of practices produces a particular cluster of physical effects, reliably, in almost everyone who does them. The practices include transcendental meditation, yoga, deep breathing exercises, mindfulness, Tai Chi, repetitive religious recitation, and silent contemplative prayer.

The effects include lower blood pressure, lower heart rate, reduced cortisol, increased heart rate variability, and a shift in the autonomic nervous system away from fight-or-flight and toward what biologists call rest-and-digest.

This is not faith healing. It's not even particularly mystical. It's what happens when a primate sits still and breathes slowly for twenty minutes. But it's real, it's measurable, and prayer in its contemplative forms is one of the practices that produces it.

What the actual measurements look like

In a Harvard study published in 2008, researchers tracked the gene expression of long-term practitioners of relaxation-response techniques and found that more than 2,000 genes were expressed differently after the practice. Genes involved in oxidative stress, inflammation, and cellular metabolism all shifted. Some of these changes were detectable after a single session in beginners. They were more pronounced in long-term practitioners.

Translation: doing this for twenty minutes a day, over years, appears to change which genes are switched on in your cells.

Other studies have measured what happens during prayer specifically:

So far, so good. The body responds. The mechanisms are increasingly well understood. The effects are real.

Now the caveat.

What these measurements do not show

Two important things are missing from this picture and a careful reader will already have noticed both.

First: almost none of these effects are unique to prayer. The relaxation response is the relaxation response, whether you reach it by reciting the Hail Mary, repeating a Sanskrit mantra, doing four-seven-eight breathing, or sitting silently for twenty minutes thinking about nothing in particular. The benefits are real but they belong to a wider category of practice that prayer is one member of.

This is not bad news. It is interesting news. It means that one of the things prayer has been doing for two millennia is putting Christians inside a category of human practice that turns out to be measurably good for them.

Second: none of this addresses the actual content of prayer. The body data tells you that something happens to your nervous system when you say the Rosary. It does not tell you whether anyone is on the other end of the line.

This is the line researchers have to be careful with, and most are. When neuroscientists like Andrew Newberg are asked whether their scans prove or disprove the existence of God, they almost always say the same thing: this is a physiology study, not a metaphysics study. We are measuring brains. What the brain may or may not be in communication with is not something we can image.

This is the right answer and the column will not improve on it.

The Rosary breathing thing is genuinely interesting

One specific finding deserves its own moment. In 2001 a team of Italian cardiologists published a paper in the British Medical Journal called "Effect of rosary prayer and yoga mantras on autonomic cardiovascular rhythms." They had noticed that the average duration of one cycle of the Ave Maria in Latin, recited at a normal devotional pace, was almost exactly ten seconds. So is the average duration of one cycle of the Sanskrit mantra Om Mani Padme Hum.

Ten seconds is six breaths per minute. Six breaths per minute happens to be the breathing rate that synchronizes baroreflex sensitivity and produces the maximum effect on heart rate variability.

The Italian team measured this carefully and concluded: yes, both practices, evolved independently across two different religious traditions, had converged on the same optimal breathing rate. People had been doing this for centuries without knowing why it worked. Their bodies had figured out what their physiology needed before anyone had the words to describe it.

This is one of those findings that makes you stop and look at it for a minute.

What this means for someone who prays

If you pray contemplatively and have wondered whether the calm you feel afterward is "real" or "just psychological," the answer from the research is that the distinction itself is a bit of a category error. The calm is real. It is psychological because it is also physiological because that's how human beings work. Your blood pressure has actually dropped. Your nervous system has actually shifted gears.

If you have never prayed and wonder whether trying it would do anything, the honest answer is: a regular practice of sustained, repetitive, attention-quieting prayer would probably do for you many of the same things mindfulness meditation has been shown to do for the people in the studies. Whether it would also do something that isn't on the instrument readings is a question for you and the tradition, not for this article.

The interesting thing, and the genuinely strange thing, is how exactly the practices that produce these effects line up with the practices the traditions evolved for completely different reasons.

The body, as it turns out, has been getting something out of this all along.