Laughter may be the best medicine, but even looking forward to having a good laugh can boost the immune system and reduce stress, U.S. researchers reported on Wednesday.

Just anticipating a happy, funny event can raise levels of endorphins and other pleasure and relaxation-inducing hormones and lower production of stress hormones, a team at the University of California Irvine said.

This team tested 16 men who all agreed they thought a certain videotape was funny. Half of them were told three days in advance they would watch it.

Those who knew in advance they would see the video started experiencing biological changes right away.

When the men watched the video, levels of cortisol, a stress hormone, fell 39 percent. Epinephrine fell 70 percent, while levels of the feel-good hormone endorphin rose 27 percent and growth hormone levels rose by 87 percent. "Growth hormone is very beneficial to the immune system," according to the team.

This all suggests that anticipation of a funny event can lower stress and stimulate the immune system, Lee Berk，an assistant professor of family medicine and researcher in complementary and alternative medicine who led the study said.

Berk and others had already shown that actually watching a funny video, or just laughing at a joke, could make healthful changes in the levels of hormones involved in stress and lower blood pressure.

"You have been thinking about it all day, so you experience a change in biology even before you get there," Berk said. "That is therapeutic."

Berk said the finding strengthens the advice that everyone lighten up a little to live longer. "Anticipation is half or two-thirds the fun," he said.

笑口常开助长寿 “笑意”盈盈也健身

笑也许是公认的最好的良药，而美国研究者11月6号公布的研究结果更显示：即便是有这种开怀大笑的愿望，也同样能够增进免疫功能，减少压力。

据加州大学欧文分校的一个研究小组研究，仅仅是期待一件快乐、有趣的事件也能提高大脑内啡素（一种令人情绪愉快的物质）的产生，并减少压力荷尔蒙的分泌。

研究小组共对16个试验者进行了研究。首先找出一部他们共同认为很有趣的电影，并提前三天告知其中一半的人将观赏该片。

研究表明，那些提前知道的人体内的化学物质随即产生了生理变化。

而当这些人观看该片时，他们体内的考的素（一种压力荷尔蒙）含量下降到39%。肾上腺素下降了70%。而令人愉快的内啡素则上升了27%，生长激素则上升了87%。而生长激素正是对免疫系统有着极大促进作用的一种荷尔蒙。

主持这一研究的家庭医学助理教授、辅助医学和替代医学领域研究者李·伯克说，这一切都表明对愉快事件的期待也能减轻压力，促进免疫系统。

伯克和他的助手已经证实，观看一部有趣的电影，或者是听到一则令人捧腹的笑话而开怀大笑都能促使体内有关压力的荷尔蒙含量得到有效控制并降低血压。

"由于你一整天都在期待着（那件有趣的事），你的身体就会在经历事件本身之前就发生生理变化。"伯克说，"这就是身体的良药"。

伯克还说这一研究结果证实了生活积极的人寿命更长这一说法。他说："乐趣有三分之二来源于对乐趣的期待。"

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