The relationship between human breathing and our minds and bodies is a long-standing scientific mystery. 

But it’s not as if we know nothing. We know that breathing, much like the heartbeat, is a mostly subconscious rhythmic process. It differs from the heartbeat, though, in that we’re able to consciously regulate elements of it at will. 

We also know there’s a powerful connection between breath and state of consciousness. Long, slow breaths have been an integral part of meditation for hundreds of years, and psychologists recommend “four-square breathing” (alternatively box breathing) in order to prevent panic attacks.

Still, what goes on at a cellular level while we breathe is, for the most part, unknown. 

Twenty-five years ago, a breakthrough study at the University of California Los Angeles discovered 3,000 interconnected neurons that control different aspects of breathing, such as yawning or sighing (this cluster is called the breathing pacemaker). But that research remained unevolved for years. At least, until recently. 

A year ago, researchers from Stanford University, UCLA, and a few other schools released a study in which they used new genetics technology to view individual neurons inside the breathing pacemaker. They identified 65 different varieties of neurons, and it is believed that each has a unique responsibility related to breathing. 

To illustrate this, the team specifically bred mice so that they would possess pacemaker cells that were vulnerable to a unique, man-made virus. This virus was designed to deactivate the pacemaker cell, therefore illuminating its purpose.  

When the mice were injected with the virus and the cell was deactivated, they quit sighing every few minutes (a subconscious breathing activity both mice and humans engage in). From this study, we began to understand what these pacemaker cells do — but even with as much as was learned, a multitude of questions arose. 

Now, the team has released a new study that exposes some of the most fundamental elements of the relationship between the respiratory system and the rest of the human body. As explained in detail below, this study illustrated that when deep breathing is present, certain neurons, which push the brain into a panicked state, do not fire off. As a result, these mice were able to stay calm and peaceful in otherwise agitating scenarios. Fascinating.

So for the newest study, which was published recently in Science, the researchers carefully disabled yet another type of breathing-related neuron in mice. Afterward, the animals at first seemed unchanged. They sighed, yawned and otherwise breathed just as before.

But when the mice were placed in unfamiliar cages, which normally would incite jittery exploring and lots of nervous sniffing — a form of rapid breathing — the animals instead sat serenely grooming themselves.

“They were, for mice, remarkably chill,” says Dr. Mark Krasnow, a professor of biochemistry at Stanford who oversaw the research.

To better understand why, the researchers next looked at brain tissue from the mice to determine whether and how the disabled neurons might connect to other parts of the brain.

It turned out that the particular neurons in question showed direct biological links to a portion of the brain that is known to be involved in arousal. This area sends signals to multiple other parts of the brain that, together, direct us to wake up, be alert and, sometimes, become anxious or frantic.

In the mellow mice, this area of the brain remained quiet.

“What we think was going on” was that the disabled neurons normally would detect activity in other neurons within the pacemaker that regulate rapid breathing and sniffing, says Dr. Kevin Yackle, now a faculty fellow at the University of California, San Francisco, who, as a graduate researcher at Stanford, led the study.

The disabled neurons would then alert the brain that something potentially worrisome was going on with the mouse since it was sniffing, and the brain should start ramping up the machinery of worry and panic. So a few tentative sniffs could result in a state of anxiety that, in a rapid feedback loop, would make the animal sniff more and become increasingly anxious.

Or, without that mechanism, it would remain tranquil, a mouse of Zen.

The implication of this work, both Dr. Krasnow and Dr. Yackle say, is that taking deep breaths is calming because it does not activate the neurons that communicate with the brain’s arousal center.

Whether deep breathing has its own, separate set of regulatory neurons and whether those neurons talk to parts of the brain involved in soothing and pacifying the body is still unknown, although the scientists plan to continue studying the activity of each of the subtypes of neurons within the pacemaker. This area of research is in its infancy, Dr. Yackle says.

It also so far involves mice rather than people, although we are known to have breathing pacemakers that closely resemble those in rodents.

But even if preliminary, this research bolsters an ancient axiom, Dr. Krasnow says. “Mothers were probably right all along,” he says, “when they told us to stop and take a deep breath when we got upset.”

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