The mere anticipation of a good laugh, it seems, can be as healthful as a rib-tickling rollick itself. Researchers led by a team from the College of Medicine at the University of California, Irvine, recently took a look at how the expectation of a funny event affected a person's stress levels and immune system function. What they found was striking. Several subjects at nearby Loma Linda University were told that they would be viewing a humorous video in three days. A control group was told nothing. In the days before show time, the participants who were informed in advance showed a 39 percent decrease in cortisol and a 70 percent drop in epinephrine, both stress hormones that can be detrimental to health. They also saw an 87 percent rise in growth hormone and a 27 percent gain in beta-endorphin. Both these compounds can reduce the effects of stress and strengthen the immune system. The control group saw none of these changes. "This has profound wellness and disease prevention implications, and may indeed constitute a real 'biology of hope,'" says lead researcher Lee Berk, Dr.PH. (doctorate in public health), an assistant professor of family medicine at the College of Medicine.