WASHINGTON—About 200 people are sitting on yoga mats in a Washington hotel ballroom trying to learn how to do something they already do about 21,600 times a day: breathe.

This “automatic breathing” they’ve been doing all their lives? No good. So they’re learning to breathe deeply from their diaphragms and hoping that benefits—such as stress reduction, better sleep and increased mental focus—will follow.

“If you’re angry and you want to be calm, what do you do? Breathe how?” asks senior teacher Rajshree Patel from a stage at the front of the room, a white orchid at her side. “The breath of rest and relaxation. And you will see the mind will shift. If you switch the rhythm of breath, it will switch the emotion.”

“Take a Breath DC” ran from Wednesday to Saturday and culminated in a group meditation for about 600 in Lafayette Park. The course was organized by the Art of Living Foundation, a nonprofit group here. The cornerstone of Art of Living is a rhythmic breathing technique called Sudarshan Kriya.

About 30 years ago, Sri Sri Ravi Shankar (not the sitarist who knew the Beatles; different guy) discovered that this type of breathing, combined with yoga and meditation, can bring inner peace; he and his followers have taught the art of better breathing to millions since then.

The DC students paid $250 for the course, which ran for 22 hours over four days. (Art of Living also teaches prisoners, high-schoolers and natural-disaster survivors how to breathe, for either a reduced rate or for free.)

The students must agree to these rules:

1. Be on time.

2. Finish the course.

3. Eat a vegetarian diet. (One muscular young man seems concerned he won’t get enough protein. “I’ll let you eat eggs,” Patel says. “Because they’re not chickens yet.”)

4. No alcohol. (“You’re going to do a lot of cleansing of the system, and you’ll find that if you’ve had alcohol the night before—or the morning or the afternoon—what happens is, in the evening, the first thing you’ll cleanse is the alcohol, and I’d like to go to deeper layers of cleansing with you.”)

5. Refrain from tobacco.

6. No recreational drugs.

Students get extra credit for avoiding caffeine.

Vincent Ko, a Georgetown University student, says, “I’m at that point where I’m going to be a senior, and I’m really stressed out about what I’m going to do for the rest of my life. I’m trying to start this business, I want to be an entrepreneur, but then, like, should I do an investment banker type of deal? So I’m just freaking out....I’m at a crossroads.”

After a break, the students learn the first breathing technique aimed at bringing the mind into the present moment: ujjayi, sometimes called “ocean breath” because it makes the sound of the sea. The 14 Art of Living instructors and 46 teachers-in-training scatter throughout the room and show the students how to breathe in and out through their noses while constricting the backs of their throats. When everyone has it down, Patel instructs them to sit cross-legged, close their eyes and practice ujjayi breath.

By the end of the four days, Ko is a believer: “It was really powerful. While we were doing meditation, I could visualize all my stress, and it stopped bothering me.”