Expectation Of Laughter Boosts Endorphins

Tipped off by a post at Crumb Trail, I saw this report on the effects of the anticipation of "mirthful laughter" on stress:

Just the expectation of a mirthful laughter experience boosts endorphins 27 percent, HGH 87 percent
Public release date: 3-Apr-2006
American Physiological Society

SAN FRANCISCO – There's no doubt that laughter feels good, but is there real neurophysiology behind it and what can you do about it?

In a paper being presented in an American Physiological Society session at Experimental Biology 2006, Lee S. Berk of Loma Linda University, reports that not only is there real science and psychophysiology, but just the anticipation of the "mirthful laughter" involved in watching your favorite funny movie has some very surprising and significant neuroendocrine/hormone effects.

According to Berk: "The blood drawn from experimental subjects just before they watched the video had 27% more beta-endorphins and 87% more human growth hormone, compared to blood from the control group, which didn't anticipate the watching of a humorous video. Between blood pulls, the control group stayed in a waiting room and could choose from a wide variety of magazines," he explained.  [...]

The article goes on to explain that they also found beneficial effects on the immune response, suggesting that there could be benefit for those with autoimmune diseases.  It's just an armchair-musing kind of speculation, but since the effect is seen with mere anticipation of something positive, I wonder if it is related to the placebo effect?