At rest, your breathing should be slow and steady, between 12 and 20 breaths per minute. Consciously slowing that even further — to between five to seven breaths per minute at rest — can help reduce blood pressure, regulate heart rate and lift mood. Researchers have also reported that breathing slowly can reduce chronic pain, stress and depression, and bolster fitness and energy levels.

One study, published last April, found that breath work helped recovering Covid-19 patients return to healthy respiratory rates.

When sick, stressed or anxious, many people start breathing rapidly from the top of the chest, which activates the body’s sympathetic nervous system, said Dr. Melis Yilmaz Balban, a neurobiology researcher at Stanford University and co-author of a study published in January on how breath work can be used to lift mood. Breathing in this way raises your heart rate, suppresses digestion and heightens the brain’s tendency to detect danger, whether real or imagined.

Many people find it difficult to slow their breathing even after a threat or source of stress has subsided, and may end up developing unhealthy breathing habits in the long term. When breath, pulse and blood pressure remain elevated, “that stressful day becomes a stressful week becomes a stressful month,” said Stuart Sandeman, a London-based coach who helps people improve their breathing and is the author of “Breathe In, Breathe Out.”

The mechanism that makes a lot of breath work effective for enhancing mental, emotional and physical health is that it forcibly slows breathing down, said Dr. Raj Dasgupta, a pulmonologist and sleep medicine specialist at Keck Medicine of University of Southern California, who uses breathing exercises with patients who have chronic lung diseases or insomnia. When you slow your breathing down, “the parasympathetic system — what we call the ‘rest and digest’ system — hopefully takes over and helps calm you down,” he said.

Additionally, “with any type of breath work, we are forced to pay attention to our breath and our internal state,” said Dr. Yilmaz Balban. “It brings you into the moment.” One study, published in November, found that even just focusing on the way you naturally breathe, when paired with other mindfulness practices, was as effective as drugs to treat anxiety disorders.

Dr. Dasgupta noted that even if you have health conditions that affect breathing, it’s safe to attempt to deepen and slow your breaths bit by bit. “When my chronic lung disease patients start having a flare up and get that feeling of shortness of breath, of course they need their medications,” he said. “But I tell them that they should also focus on using that diaphragm muscle and slowing down the respiratory rate.”

The recent research into breathing upholds what “yogis and meditators have been talking about for thousands of years,” Mr. Sandeman said. “These older traditions knew the benefits of breathing well,” he added, and Western medicine is just beginning to catch up.

So, how do you get started? Here are three simple breathing exercises that the pulmonologists, sleep doctors and researchers consulted for this story recommend.