Illustration: Kieran Blakey

The Nuance

A Single Deep Breath Is the Quickest Way to Relieve Stress

It’s a great way to stimulate the vagus nerve — and induce a state of calm

TThe way a person breathes is inextricably linked to the way a person feels. This is a central tenet of several forms of Eastern medicine as well as everything from yoga and meditation to tai chi and karate. Each of these disciplines emphasizes the primacy of careful and controlled breathing for the health and function of the body.

While Western medicine has long recognized shallow, rapid, or otherwise disordered breathing as a symptom of illness, breathing was not traditionally viewed as a modifiable factor in an ailment’s progression or treatment. But that’s changing. The last two decades have witnessed a surge in breathing-related interventions for pain- and anxiety-related disorders, as well as for diseases of the gut, heart, and brain. The more doctors explore breathing as a form of illness prevention and therapy, the more they turn up evidence of its importance.

One 2012 study in the journal Pain Medicine found that five-minute periods of deep breathing led to statistically significant improvements in pain detection and tolerance among healthy adults. And a 2005 study found that two minutes of slow, controlled breathing led to a 6% drop in blood pressure scores among people with hypertension.

The research on respiration also extends to the brain. One 2015 study in the journal Clinical Interventions in Aging found that six months of breathing training, but not exercise, led to improvements in mental flexibility and other measures of cognitive functioning among seniors. Research has also found that slow, deep breathing improves a person’s memory retention.

The authors of all of these studies highlight the breath’s calming, stress-lowering powers as the likeliest explanation for its beneficial effects. And this makes sense: The bulk of the research on breathing exercises has focused on their ability to combat anxiety and stress.

“Breathing is the only physiological function that is under our voluntary control, and slowing the breath has profound and immediate physiological effects,” says Irina Strigo, an associate professor of psychiatry at the University of California, San Francisco’s Weill Institute for Neurosciences.

Some of Strigo’s work has explored the way “paced” breathing affects homeostasis within the body and brain, and specifically the way slow, deep breaths calm the internal systems that fire up when a person experiences stress. She says that slow and deliberate breathing “puts the brakes” on the activity of the sympathetic nervous system, which is the branch of the central nervous system that governs the body’s fight-or-flight response.

Deep and prolonged exhalation — basically, emptying the lungs — is the thing that seems to stimulate the vagus nerve most, and thereby induce a state of calm.

When a person feels threatened (whether that threat is physical, social, or emotional), the resulting stress kicks the sympathetic nervous system into gear. Stress-related hormones like cortisol flood the blood and cause heart rate and breathing to accelerate. Meanwhile, muscles grow tense, digestion slows, and the immune system releases inflammation-stoking cells. The whole body more or less clenches, as though preparing to engage in physical combat.

While all of these internal fight-or-flight processes are helpful in an emergency, long-term and frequent activation of the sympathetic nervous system is associated with out-of-control inflammation and an increased risk for illnesses ranging from diabetes and heart disease to depression and autoimmune disorders.

Slow, deep breathing seems to counteract all of these stress-triggered processes. Strigo says deep breaths seem to do this by stimulating the vagus nerve, which is a component of the parasympathetic nervous system that governs the body’s relaxation responses. “All of these systems are interrelated,” she says. By mellowing one component of sympathetic nervous system activity — the breath — a person can basically power down the whole apparatus of stress, she says.

In support of this theory, a 2017 study led by researchers at Stanford University found that destroying specific breathing-regulating neurons in the brains of mice left the animals almost imperturbable, but otherwise unharmed. Shutting down these respiratory neurons seemed to turn off “higher-order brain structures” involved in stress and arousal, the authors of that study wrote.

“If you stop breathing for just a few seconds — hold your breath — your heart rate will go up and you’ll start feeling anxious,” Strigo says. On the other hand, she says a single long, slow breath is enough to ease tension, reduce heart rate, and calm anxiety. “For stress-reduction, even one deep breath is really effective.”

A proper deep breath involves slow and steady inhalation — think gradual, not urgent — followed by slow and steady exhalation. Good posture — shoulders back, head up —also facilitates proper breathing. Strigo adds that deep and prolonged exhalation — basically, emptying the lungs — is the thing that seems to stimulate the vagus nerve most, and thereby induce a state of calm.

While a single breath is helpful, her and others’ work has shown that breathing at a rate of around five breaths per minute for anywhere from 30 seconds to 15 minutes is an effective way to turn off stress.

“It’s really remarkable how many disorders are associated with irregular breathing,” she adds. “Once you start paying attention to your breathing, you see how it changes depending on how you feel, and how much modifying it can help.”

I write about health and science. I live in Detroit with my wife and kids. I’m trying to learn German, but my progress so far is nicht gut.

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