Doctor’s orders? ‘Belly laugh at least two to five days a week’

The laughter clubs were based on the common-sense notion that laughter relieves stress. But a good laugh is also good for your heart, immune system and many other health benefits, said Dr. Michael Miller, a cardiologist and medical professor at the University of Pennsylvania.

“Like we say, exercise at least three to five days a week,” Miller said. “Belly laugh at least two to five days a week.”

Miller began studying laughter in the 1990s. Showing funny movies to study participants, he found that laughter produces endorphins in the brain that promote beneficial chemicals in the blood vessels. Nitric oxide, for example, causes blood vessels to dilate, which lowers blood pressure, inflammation and cholesterol.

The combination reduces the risk for a heart attack, he said, and the endorphins are natural pain killers.

“When you’ve had a really good laugh, you feel very relaxed and light,” said Miller, who is also chief of medicine at the Philadelphia Veterans Administration, where he is implementing a laughter therapy program. “It’s like you’ve taken pain medication.”

Forced laughter — or simulated mirth, in academia — may even be more beneficial than spontaneous laughter, said Jenny Rosendhal, a senior researcher of medical psychology at Jena University in Germany.

Rosendhal completed a meta-analysis of 45 laughter studies, among other research, and found that laughter-inducing therapies decreased glucose levels, the stress hormone cortisol and chronic pain. They also improved mobility and overall mood, especially in older populations.

Because humor is subjective, it is hard to measure. That’s why much of the more recent research has focused on laughter yoga and similar programs that provoke sustained bouts of laughter during 30- to 45-minute sessions, Rosendhal said.

Laughter yoga is particularly effective for people who might not feel like laughing, such as those struggling with depression or cancer patients, she said. With simulated laughter, the physiological mechanisms are the same, such as additional inhaling, exhaling and muscle activity that also improves mood.

“The well-being comes through the back door,” she said. “You start with an exercise, and then the spontaneous laughter comes later because it’s funny to see people laughing.”