BEING happy and enthusiastic makes you less likely to develop heart disease, a study suggests.
It is believed that the study is the first to show such an independent relationship between positive emotions and heart disease.
Lead researcher Dr Karina Davidson said boosting people's positive emotions could be the key to reducing heart disease
The new study, published in the European Heart Journal, focused on 1,739 healthy adults assessed over ten years.
Nurses assessed participants' risk of heart disease and measured symptoms of depression, hostility, anxiety and the degree of expression of positive emotions, known as "positive affect".
This positive affect is defined as the experience of pleasurable emotions such as joy, happiness, excitement, enthusiasm and contentment.
These feelings can be short-lived, but they are usually stable character traits, particularly in adulthood, the study said.
After taking account of age, sex, heart-associated risk factors and negative emotions, researchers found that increased positive affect predicted a 22 per cent lower risk of heart disease.
Dr Davidson said: "Participants with no positive affect were at a 22 per cent higher risk of heart disease than those with a little positive affect, who were themselves at 22 per cent higher risk than those with moderate positive affect."
Dr Davidson said there were several possible explanations for the link between happiness and heart health.
"First, those with positive affect may have longer periods of relaxation physiologically," she said.
"Second, those with positive affect may recover more quickly from stressors, and may not spend as much time 're-living' them, which in turn seems to cause physiological damage."
The researchers, from the Columbia University Medical Centre in New York, said further clinical trials were needed before doctors could start giving advice to patients on being happier to improve their heart health.
Dr Davidson said everyone should try to inject some fun into their daily routines.
She said: "Some people wait for their two weeks of vacation to have fun, and that would be analogous to binge drinking.
"If you enjoy reading novels, but never get around to it, commit to getting in 15 minutes or so of reading. If walking or listening to music improves your mood, get those activities in your schedule.
"Essentially, spending some few minutes each day truly enjoying yourself is certainly good for your mental health, and may improve your physical health as well."
The British Heart Foundation welcomed the findings, but said more work was needed.
Ellen Mason, a senior cardiac nurse, said: "We don't know if it's possible to change our natural levels of positivity."