“Giving thanks” actually expresses gratitude¹ to another person, whether verbally, physically², or even in the form of a letter - has profound effects on us, not just mentally but physically.

Ungrateful people are actually cheating themselves, scientists believe.

The mere³ act of thanking people releases chemicals within the body including “reward” chemicals such as dopamine and serotonin - a neurotransmitter that makes us feel serene⁴ and happy.

“If thankfulness were a drug,” says Dr P Murali Doraiswamy, of Duke University, “It would be the world's best selling product. It affects every major organ system.”

Stress hormones⁵ such as cortisol are also reduced by the simple act of thanking someone.

Another study at Kent State University, Salem, measured the effect.

Steve Toepfer had a sample group of students write letters of gratitude to people they knew.

Toepfer ensured the “thanks” weren't for trivial events such as a gift, but for genuine, meaningful events.

One group of students didn't write letters, one did.

The group that wrote the letters found that their levels of life satisfaction increased - and that those who were experiencing mild depression found that their symptoms abated⁶.

The key, it seems, is genuine gratitude: your body has to “know” that a positive event has occurred, and that you've responded.

“If you're looking to increase your well-being⁷, take 15 minutes to write letters of gratitude to someone,” said Toepfer, who published his study in the Journal of Happiness Study.

据英国《每日邮报》11月23日报道，“给予感谢”实际上表达了我们对他人的谢意。无论是通过语言，行动还是书信的方式表达谢意，对我们造成的深远影响不仅有精神层面的，还包括生理层面的。

科学家们认为，不知感恩的人实际上是自欺欺人。

纯粹地向人致谢能使体内释放出化学物质，包括像多巴胺与血清素一类的“奖励”物质。血清素是一种能使人感到平静和快乐的神经递质。

美国杜克大学的P-穆拉利-多雷斯瓦米博士说：“如果感谢是一种药，它会是世界上最畅销的药品。它影响到人体每一个重要的器官系统。”

简单的致谢行为还能减少如皮质醇一类的压力荷尔蒙。

另一项研究来自美国肯特州立大学的赛勒学院，该研究检测了感谢行为带来的影响。

史蒂芬-托普菲尔让一个学生实验小组给他们认识的人写感谢信。

托普菲尔确保这些“感谢”针对的不是如收到一件礼物的小恩小惠，而是真实的有意义的事件。

一组学生写了感谢信而另一组则没有。

写了感谢信的小组成员发现他们的生活满意度有所提高，而那些曾经历过轻度抑郁的学生发现自己的抑郁症状有所减轻。

这种情况出现的关键似乎就是真诚的感激之情：你的身体已经“知道”发生了一件积极的事件，而这些反应正是身体的回应方式。

托普菲尔已经把他的这项研究发表在了《幸福感研究》上，他说：“如果你想增加幸福感，就花上15分钟写一份感谢信吧。”