Don't worry, be happy and, according to new research, you will also be healthy.

It is estimated that over the course of one year, Americans suffer 1 billion colds. But new research shows that all it may take to avoid this common affliction is a positive and upbeat attitude.

People who are energetic, happy and relaxed are less likely to catch a cold than those who are depressed, nervous or angry, finds a new study published in the journal Psychosomatic Medicine.

Healthy volunteers first underwent an emotional assessment in which they were asked to rate their tendency to experience positive and negative emotions--how often they felt pleased, relaxed, happy, or anxious, depressed and hostile. The subjects were next given a squirt up the nose of a rhinovirus, the nasty little germ that causes colds.

Researchers then watched the volunteers to see who came down with a cold and waited to see how the unlucky ill manifested their cold symptoms.

"We found that people who regularly experience positive emotions, when exposed to rhinovirus, are relatively protected from developing illness," said Dr. Sheldon Cohen, lead author of the study and a psychology professor at Carnegie Mellon University.

Although positive people showed a greater resistance to colds, negative people did not necessarily get sick more often.

"Increases in positive emotional styles were linked with decreases in the rate of clinical colds, but a negative emotional style had no effect on whether or not people got sick," Cohen said.

So how can your emotions influence your health? In simple terms, when the brain is "happy" it sends messages to our organs that help keep the body healthy and sound.

"It's like a drug that is released by your state of mind and simply changing the state of mind can produce effects on the rest of the body through the nervous system and hormones," said Dr. Neil Shulman, associate professor of medicine at Emory University School of Medicine and author of Doc Hollywood. "Your chance of developing the common cold, pneumonia, or even cancer may very well be decreased by keeping your brain in a healthy state."

In addition, happy and relaxed people are prone to better health practices than their negative and stressed counterparts. They are more likely to get plenty of sleep and to engage in regular exercise, and have been shown to have lower levels of certain stress hormones.

Shulman says the study shows there are some simple things you can do to improve your chances of staying healthy.

"The take-home message is that we have very healthy ways that we can improve our overall well-being that don't cost money and that don't require a wait in the doctor's office," he said.

根据新的研究结果显示，如果你心情愉快、无忧无虑，你就会身体健康。

据估计，美国一年中有十亿人患感冒。而新的研究表明只要有积极乐观的态度，就可以避免这一常见的疾病。

《心理医学》杂志发表的一项新的研究表明：精力充沛、快乐轻松的人和沮丧、紧张、易怒的人相比不容易得感冒。

身体健康的志愿者们首先接受了一次情绪测试，来测定他们的情绪是趋向于积极的还是消极的，也就是他们感到高兴、舒适、快乐或是焦虑、沮丧、敌对的频率。接着志愿者的鼻子上方被喷射一种能够引起感冒的可恶的微小细菌——鼻病毒。

然后研究者们观察那些志愿者，看谁先感染上感冒，并等着看那些不幸患病的人表现何种感冒症状。

该研究的主要领导者、卡内基梅隆大学的心理学教授谢尔登·科恩博士说：“我们发现情绪一贯积极乐观的人遭受鼻病毒侵袭时，相对来说不太容易感染疾病。”

尽管积极的人对感冒表现出较强的抵抗力，消极的人也不一定更容易经常感冒。

“情绪越乐观，感冒的几率就越低，但是消极的情绪并不会对是否感冒产生影响。”科恩说。

那么情绪到底是怎样影响你的健康的呢？简单的说，当大脑“轻松愉快”的时候，它会向各个器官发出有助于保持身体健康的信号。

“这就像是你的情绪释放的一种麻醉剂，只要改变情绪就可以通过神经系统和激素对身体的其他部分产生影响，” 埃莫里大学医学院的医学副教授、影片《好莱坞医生》的作者尼尔·舒尔曼博士说，“保持健康的情绪可以有效地降低感冒、肺炎甚至癌症发生的可能性。”

另外，心情轻松愉快的人往往比消极紧张的人有更好的保健习惯。他们更容易有充足的睡眠，进行有规律的身体锻炼，而且他们体内某种紧张激素的含量较低。

舒尔曼说研究显示你可以通过做一些简单的事情来保持身体健康。

他说：“我们的建议是通过健康的方法来改善整个健康状况，这不需要花钱也不需要在医生的办公室前等待。”