Studies suggest optimists live longer and enjoy better health than pessimists. The real mystery is why.

Among the findings of various studies:

Highy optimistic people have significantly lower death rates. Optimistic coronary bypass patients are half as likely as pessimists to require re-hospitalization.

People with positive emotions have lower blood pressure. The most pessimistic men are more than twice as likely to develop heart disease compared with the most optimistic.

But is it optimism that makes people healthy, or do healthy people understandably have a brighter outlook?

To get a better handle on things, scientists have adjusted their analyses in recent years to account for pre-existing medical conditions. Studies that made these adjustments found that existing illnesses don't negate the benefits of optimism, according to the May 2008 issue of Harvard Men’s Health Watch.

In one example of how humans keep their spirits up no matter what, researchers found older people suffering various illnesses still said they thought they were aging well. Another study found that the sick and disabled don't wallow in misery as is commonly believed.

Optimism, another study found, triggers activity in the same brain area that is known to malfunction among the depressed.

But why is optimism so beneficial?

Perhaps optimists enjoy better health and longer lives because they lead healthier lifestyles, build stronger social support networks, and get better medical care, the Health Watch article suggested.

Also, stress is known to kill, releasing hormones that cause deterioration of everything from your gums to your heart. Optimists might have lower levels of stress hormones.

Heredity could play a role, too. It is possible that genes predispose some people to optimism, and that the same genes affect health and longevity.

More study is needed, the Health Watch article contends, because it's likely that multiple mechanisms are involved.
多項研究表明，樂觀者比悲觀者更健康長壽。可其中的原因卻一直是個謎。

各項研究結果顯示：

十分樂觀的人死亡率明顯較低。在接受過心臟搭橋手術的病人中，樂觀的病人再次入院的幾率為悲觀者的一半。

情緒樂觀的人血壓相對較低。最悲觀的人患心臟病的幾率為最樂觀者的兩倍多。

可問題在于，究竟是樂觀讓人健康還是健康的人更加樂觀？

為了弄清這一問題，近年來科學家們調整了研究方法以解釋現有疾病（對樂觀情緒的影響）。據今年5月號的《哈佛男性健康觀察》，經調整后的研究發現，現有的各種病癥不會影響樂觀情緒的積極作用。

其中一項研究對人們在任何情況下如何保持樂觀情緒的問題進行了探究，研究人員發現一些受多種疾病困擾的老年人仍然覺得自己過得很好。另一項研究發現，病殘人士并不像人們通常想像的那樣郁郁寡歡。

還有研究發現，樂觀能刺激抑郁人士腦部功能紊亂區域的活動。

但為什么樂觀如此有效呢？

這篇在《哈佛男性健康觀察》上發表的文章稱，樂觀者更健康長壽也許是因為他們的生活方式更健康，社會支持網絡更有力，得到的醫療護理更好。

此外，大家都知道，壓力具有很強的“殺傷力”，它能釋放出讓你從牙齦到心臟全身各個器官都衰竭的激素，而樂觀者體內的壓力激素水平則相對較低。

另外，遺傳可能也是原因之一。可能基因會讓一些人天生樂觀，同時這些基因又會影響健康和壽命。

該文章指出，（完全解釋這一現象）還需進行更多研究，因為這一現象可能涉及多種原理。