A large new study has found that people who regularly took a siesta were significantly less likely to die of heart disease.

" Taking a nap could turn out to be an important weapon in the fight against coronary mortality, " said DimitriosTrichopoulos of the Harvard School of Public Health in Boston, who led the study published yesterday in the Archives of Internal Medicine.

The study of more than 23, 000 Greek adults -- the biggest and best examination of the subject to date found that those who regularly took a midday siesta were more than 30 percent less likely to die of heart disease.

Other experts said the results are intriguing. Heart disease kills more than 650, 000 Americans each year, making it the nation's No. 1 cause of death.

" It's interesting. A little siesta, a little snooze may be beneficial, " said Gerald Fletcher, a cardiologist at the Mayo Clinic in Jacksonville, Fla. , speaking on behalf of the American Heart Association. " It's simple, but it has a lot of promise. "

While more research is needed to confirm and explore the findings, there are several ways napping could reduce the risk of heart attacks, experts said.

" Napping may help deal with the stress of daily living, " said Michael Twery, who directs the National Heart Lung and Blood Institute's National Center on Sleep Disorders Research. " Another possibility is that it is part of the normal biological rhythm of daily living. The biological clock that drives sleep and wakefulness has two cycles each day, and one of them dips usually in the early afternoon. It's possible that not engaging in napping for some people might disrupt these processes. "

Researchers have long known that countries such as Greece, Italy and Spain, where people commonly take siestas, have lower rates of heart disease than would be expected. But previous studies that attempted to study the relationship between naps and heart disease have produced mixed results. The new study is first to try to fully account for factors that might confuse the findings, such as physical activity, diet and other illnesses.

" This study has a number of advantages, " Trichopoulos said. He and colleagues at the University of Athens examined 23, 681 Greek men and women ages 20 to 86 who had no history of heart disease or any other serious health problem when they enrolled in the study between 1994 and 1999. The researchers asked the participants whether they took midday naps and, if so, how often and for how long. They also asked detailed questions about their health and lifestyles, such as whether they had any illnesses that might make them sleep more, how much exercise they got and what they ate.

After an average of more than six years of follow-up, 792 of the study subjects died, including 133 who died of heart disease. Of that group, 94 were nappers. After the researchers accounted for factors that could confuse the issue, they found that those who took naps frequently were 34 percent less likely to die of heart disease than those who did not. The biggest nappers- 79 people who took a siesta for 30 minutes or more at least three times a week-had a 37 percent lower risk.

Naps appeared to offer the most protection to working men: Those who took midday siestas either occasionally or systematically had a 64 percent lower risk of death from heart disease. Non-working men had a 36 percent reduction in risk. A similar analysis could not be done in women because too few died of heart disease.