Take a deep breath and relax.

Behind that common piece of advice is a complex series of physiological processes that calm the body, slow the heart and help control pain.

Breathing and controlling your breath is one of the easiest ways to improve mental and physical health, doctors and psychologists say. Slow, deep and consistent breathing has been shown to have benefits in treating conditions ranging from migraines and irritable bowel syndrome to anxiety disorders and pain.

“If you train yourself to breathe a little bit slower it can have long-term health benefits,” said Murali Doraiswamy, a professor of psychiatry at Duke University Medical Center in Durham, N.C. Deep breathing activates a relaxation response, he said, “potentially decreasing inflammation, improving heart health, boosting your immune system and maybe even improving longevity,”

To help foster the habit of healthful breathing, a San Francisco technology startup recently launched a wearable device called Spire that tracks breathing patterns and tells users when they are too tense or anxious. “One of the goals of this work was, ‘How do you make it so simple to shift into calm or focus that people don’t have to stop what they’re doing?’” said Neema Moraveji, co-founder of Spire and director of the Calming Technology Lab at Stanford University.

Many early buyers of the $150 Spire are office workers who spend a lot of time on computers. Research has found people working on computers often hold their breath, an action referred to as screen apnea, he said.

Belisa Vranich, a New York City-based clinical psychologist, has been conducting breathing workshops around the country for just over a year. Among her biggest clients: corporate managers eager to learn how to better manage stress.

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