Adults forget the value of laughter, says Tita Begashaw. "Adults laugh about 30 times a day, children 300 times a day. Go back! Act like a child!" Begashaw exhorts co-workers and patients at her biweekly laughter yoga class at Harborview Medical Center in Seattle.

Scientists aren't sure what physiological and emotional mechanisms of laughter might confer a health benefit. "Is it the laughter itself? The humor (in your brain)? The community that laughter attracts?" wondered Susan Collins, a UW Medicine specialist in psychiatry and behavioral medicine.

Both women speak in this downloadable video segment.