We already know that if we quit smoking and get more exercise our health will improve. But there is mounting scientific evidence that we should take active steps to increase our happiness as well, as it may be nearly as important in helping us achieve longer, healthier lives.
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To benefit, we need to develop positive emotions over the long term. Thinking positive thoughts for a month after you've received been diagnosed with heart disease won't cure it. But lowering your stress level over a period of years by adopting a positive outlook and practicing relaxation techniques could reduce your risk of ever contracting a cardiac condition.
Be Happy, Live Longer?
A review of 19 scientific studies on the relationship between mood and longevity, published by Dutch sociologist Ruut Veenhoven in 2008, illustrates the power of happiness. At the beginning of the long-term studies, individuals rated their mood and satisfaction with life. Those who reported the highest level of satisfaction appeared to gain as much as 7.5 to 10 years of life. That's equivalent to the improved life expectancy of a smoker quitting cigarettes by age 35.
The most compelling long-term evidence of the impact of happiness on longevity comes from a report known as the "Nun Study," published in The Journal of Personality and Social Psychology in 2001, in which University of Kentucky researchers reviewed one-page autobiographies written by young women entering the American School Sisters of Notre Dame order. Years later, the analysts found a strong association between the expression of positive emotions in the essays — including love, hope, gratefulness and contentment — and the nuns' eventual longevity.
Women whose writing scored in the upper 25 percent for the use of positive emotional words lived 9.4 years longer than those in the lowest 25 percent, and women who expressed the most positive emotions lived 10.7 years longer than those expressing the fewest. (The Nun Study continues, now at the University of Minnesota.)
How Happiness Impacts Health
Beyond the impact on longevity, there is evidence linking positive emotions to a lower risk of certain diseases. In a study of older Mexican-Americans published in Psychosomatic Medicine in 2006, subjects who scored higher in reported positive emotions had significantly lower blood pressure than others in the group.
Similar studies have found that people who are generally hopeful or curious appear to have a lower risk of developing hypertension and diabetes.
How do positive emotions help us? Do happy people simply take better care of themselves?
That may be part of the answer, but even those who don't have the healthiest lifestyles reap the benefits of positivity. As a 2008 report from the Baltimore Longitudinal Study of Aging found, even after adjusting for the expected health risks of obesity and smoking, positive personality traits still appeared to increase subjects' longevity.
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It may be that positive emotions help to undo the real physical stress of negative feelings. Chronic anger, worry and hostility have been widely linked to a higher risk of developing heart disease, primarily because these emotions raise blood pressure and stiffen blood vessels. Researchers such as Barbara Fredrickson of the University of Michigan have documented that positive emotions can reverse some of the health-damaging cardiovascular reactions instigated by emotions like anxiety, anger and fear, including an increased heart rate and blood pressure.
Happiness Fades, So Keep Seeking It
We all know that happiness can be fleeting. Remember how great it felt the last time you got a raise? Do you still feel the same elation about it today? Probably not.
Psychologists have long noted the human tendency to adapt to new circumstances, whether positive or negative. Something that initially delights you eventually comes to feel like the norm. The initial sense of happiness fades and an urge to acquire the next bigger or better thing once again takes hold.
The pursuit of happiness has been called the "hedonic treadmill," because you may feel that you have to keep exerting yourself to stay in the same place.
To look at it another way, research by positive psychologist Sonja Lyubomirsky of the University of California, Riverside, has found that 50 percent of our personal happiness can be traced to genetic factors, traits that determine our mood just as some genes influence our height, for example. An additional 10 percent, on average, appears to be based on such circumstances as job, home or marital status. The last, crucial 40 percent of our potential happiness is under our control. We have to work to maintain it — and the research says it's worth the effort.
(MORE: Scientific Proof That Happiness Is a Choice)
But it isn't easy. Classic studies in the field show how even lottery winners, just one year later, score no higher on standard measures of happiness than a control group of non-jackpot recipients. Long-term studies in Germany have found that getting married initially increases individuals' happiness, but after about two years, people return to their pre-marital level of satisfaction.
For better or worse, then, we remain resilient, although some research indicates that negative events have a more enduring impact on our mood than positive ones. Certain major setbacks, like unemployment, divorce or the death of a spouse, lead to such long-lasting declines in happiness that even years later some people do not fully recover their previous levels of satisfaction. And studies of more ordinary circumstances have found that the negative impact of a typical "bad" day tend to linger more than the positive feelings after a "good" day.
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Lyubomirsky says the evidence to date indicates that we adapt more quickly and completely to positive changes in our lives, like winning a lottery, than we do to negative ones, like losing our job. This natural adaptation, she believes, forms a significant barrier to achieving durable happiness. All the more reason to commit to the positive pursuits that improve our outlook and health.
One encouraging sign: Happiness is not dependent on youth. In a study published by economist Richard Easterlin in 2006 in the Journal of Economic Psychology, not only did youth fail to contribute to happiness, but adults grew steadily happier as they moved into and through middle age, with happiness levels only beginning to decline when health problems emerged in later life.
It's not too late to pursue your own happiness today.