Breathe. To laugh. Be happy. The science behind laughter yoga

ATLANTA (CNN) – Jokes can be heard far beyond the private garden brick walls that host a laughing yoga session in Atlanta.

One beautiful weekend morning, at the height of the hottest summer in Georgia, a group of about 40 students is visibly invigorated.

At intervals, they sing or hit, frolicking in a large open circle while deliberately seeking eye contact with the nearest person – probably a person they just met.

Welcome to the yoga of laughter.

The practice, designed by India's Madan Kataria in 1995, combines playful group exercises and deep breathing to promote well-being, happiness and lots of laughter.

"It's what is called laughter yoga because of the diaphragmatic breathing that occurs when we laugh," says Celeste Greene, director of Laughter Yoga Atlanta. "It's a complete inhalation and a complete expiration."

In the beginning, laughter is simulated, or "voluntary laughter" in the language of yoga, but slowly, when students warm up, it becomes authentic and contagious.

"You can react from a place of laughter, as opposed to a stressful place.How does it sound?" Greene calls.

A group "Yeah!" follows quickly.

Next, Greene demonstrates a new exercise – "laughing at the traffic". Students pretend to drive a "car powered by laughter".

"The goal of Laughter Yoga is to build a daily habit and bring more laughter into your life," Greene explained. "It can be laughing in traffic and it could make you laugh while cleaning the house The more you laugh, the more you can laugh at what life brings."

A comic strip and a neuroscientist enter a bar

Neuroscientist Sophie Scott spent 18 years studying laughter. She is a professor at University College London by day and, on occasion, a night comedian.

"One of the great things about laughter is that it's really fun to laugh," Scott said. "You get a change in the absorption of endorphins in natural circulation, and these are the body's pain relievers – you get a measurable increase in your ability to tolerate pain."

Overtime, according to Scott, laughter can decrease the production of cortisol by the body, a hormone released by the adrenal glands into the bloodstream in times of stress. High levels of cortisol have been associated with weight gain and memory loss.

Laughter, the universal language

Back in the garden of Atlanta, strangers leave as friends at the end of the yoga session.

"It really gave me morale, as I did not expect," said David Randolph, a student in radiation oncology. "We laughed, we made eye contact, it was really nice to connect with all those people I had never met before."

Many in the group echoed Randolph's experience.

In his classes, Greene has witnessed the positive effects this group dynamics can have on a person experiencing anxiety, depression or isolation.

On the emotional level, neuroscientist Scott said that laughter can be a bonding experience between family, colleagues, friends and strangers.

"When people laugh, it's a sign that they feel comfortable, relaxed and safe and that they are not exposed," she said.

"Humans seem to be truly united by laughter."

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