There's new evidence that happiness and health may overlap.

In a recent study of British civil servants, the happiest participants had lower levels of the stress hormone cortisol. Their hearts kept a mellower pace than those of less happy participants, and they didn't flip out as much during a mental stress test.

Happiness might even hedge against heart disease, suggests the study in Proceedings of the National Academy of Sciences. Under stress, the happiest participants had lower increases of plasma fibrinogen, a sign of inflammation that can predict heart disease.

"Our findings indicate that positive affective states are related to favorable profiles of functioning in several biological systems and may thereby be relevant to risk of development of physical illness," says the study.

Translation: Being happy may be good for your physical health.

Homing In on Happiness

Participants were 216 government employees in London. They were white, 45-59 years old, more than three years away from retirement, and hadn't been diagnosed with heart disease or high blood pressure. The women were all starting or had completed menopause.

Blood pressure and heart rate were monitored on a workday and a weekend day. The researchers measured levels of blood fibrinogen and saliva cortisol -- a stress-related hormone that increases the risk of heart disease and diabetes.

Measurements were taken after a mental stress test. After each test, participants rated their happiness level on a scale of 1 (low) to 5 (high).

Happiness Advantage

The happiest people in the group had the best results across the board.

For instance, their levels of the stress hormone cortisol averaged 32% lower than the least happy people. Happiness was also associated with lower ambulatory heart rate, even after considering other factors (age, smoking, employment level, BMI, and physical activity).

During the mental stress tests, most participants (68 percent) had an increase in plasma fibrinogen. The least happy people were nearly four times (3.72) as likely to have their plasma fibrinogen level increase under stress, compared to the happiest people.

Apart from the stress test, plasma fibrinogen was not associated with happiness, report the researchers, who included Andrew Steptoe, DPhil, DSC, of University College London. Steptoe specializes in psychology and health.

Working for the Weekend?

Taking readings on a workday and during weekend leisure time showed if participants were happier on or off the job.

For those with lower happiness levels, that was true to some degree. But the happiest people generally stayed that way, whether they were on the job or not.

The study amounted to a snapshot of happiness. It wasn't a long-term project, so there's no information on how the findings translate into health outcomes later on.

Age, sex, marital status, and socioeconomic position were not associated with happiness level. That is, happiness didn't favor people who were married, single, male, or female. It wasn't just for those with the biggest salaries or most status, or just for the young or old (though the group was middle-aged, overall).

Strengthening Happiness

The study doesn't prove that happiness was responsible for those outcomes. Not everyone who's happy is healthy, or vice versa.

Got some room for improvement in the happiness department? These tips may come in handy:

--Realize that enduring happiness doesn't come from success as it's often defined.

--Take control of your time.

--Act happy.

--Seek work and leisure that engages your skills.

--Get aerobic exercise.

--Get enough sleep.

--Give priority to close relationships.

--Focus beyond yourself.

--Appreciate what you have.

--Try keeping a gratitude journal of what you're thankful for.

--Nurture your spiritual self.

--Tell positive stories about your life. Tell the truth, but look for the good. Live a multidimensional life.

--Focus on your choices and any power you have in your situation.

--Find and lead with your strengths.

That advice comes from David G. Myers, PhD, a psychology professor at Michigan's Hope College, and Dan Baker, PhD, a medical psychologist at Canyon Ranch. Myers' books include The Pursuit of Happiness; Baker wrote What Happy People Know.

Doctors and therapists are also good resources. Don't hesitate to ask for help, especially if you suspect depression.

By Miranda Hitti, reviewed by Brunilda Nazario, MD

SOURCES: Steptoe, A. Proceedings of the National Academy of Sciences, early edition. News release, Proceedings of the National Academy of Sciences. WebMD Medical News: "Make Room for Happiness." davidmyers.org, "Suggestions for a Happier Life." Baker, D. and Stauth, C. "What Happy People Know." HarperCollinsPublishers Australia, June 2003.