If you believe it is on the full side you may live longer and enjoy better health. At least that is what several studies suggest. The findings in various studies have shown that highly optimistic people have significantly lower death rates.

Coronary bypass patients who view life optimistically are half as likely as pessimists to require re-hospitalization. People with positive emotions have lower blood pressure. And, pessimistic men are more than twice as likely to develop heart disease compared with the most optimistic.

The real mystery is why. According to the May 2008 issue of Harvard Men's Health Watch, scientists have adjusted their analyses in recent years to account for pre-existing medical conditions. These studies found that existing illnesses don't negate the benefits of optimism.

One example given in the article is how humans keep their spirits up no matter what. Researchers found older people suffering from different illnesses still said they thought they were aging well.

Another study, says the article, found that the sick and disabled won't wallow in misery as commonly believed.

In yet another study, optimism was found to trigger activity in the same brain area that is known to malfunction among the depressed.

So why is optimism so beneficial? The article suggests that optimists live longer and better lives because they have healthier lifestyles, get better medical care and have strong social support networks.

Heredity may also play a role. It's possible that a person's genes may predispose some people to optimism, and that the same genes affect health and longevity.

Reversely, stress is known to kill, releasing hormones that created deterioration of everything from your gums to your heart. Optimists may have lower stress hormones.

The magazine article contends that more study is needed and most likely multiple mechanisms are involved. So next time you see that glass, you might want to remind yourself to see it as "half full" rather than empty.