Presidential candidates may want to be careful what they wish for, because winning the election might not be good for their health, new research suggests.

In a study of elected presidents and prime ministers from 17 countries, the winners typically lived 2.7 fewer years and had a 23 percent greater risk of premature death than runners-up who never served in their nation's highest office, according an analysis of more than 300 leaders spanning nearly three centuries.

"The increase in mortality among those leading a nation, relative to others in politics, may stem from the greater responsibility and stress of the job," said senior study author Anupam Jena of Harvard University and Massachusetts General Hospital in Boston. "The decisions are more impactful, the spotlight is greater, and I suspect the job is even more strenuous."

In the U.S., for example, presidents lived 12 years on average after their last election, while runners-up lived about 19 years, Jena added by email. After accounting for the fact that the election winners tended to be a bit older than the losers, U.S. presidents still lived about 5.7 fewer years.

It's hard to say exactly why being president or prime minister might make somebody prematurely gray or send them to an early grave, but stress is likely involved, Jena said."Certain hormones like cortisol may be elevated, which in turn accelerate diseases such as cardiovascular disease," Jena added. "Reducing stress would arguably slow the acceleration of aging but may not fully reverse it."

Jena and colleagues examined survival differences between elected world leaders and the candidates who tried and failed to win office from 1722 to 2015 in Australia, Austria, Canada, Denmark, Finland, France, Germany, Greece, Ireland, Italy, New Zealand, Norway, Poland, Spain, Sweden, the UK and the U.S.

"Those living in the highest 1 percent of the population in income, education and socioeconomic status tend to live significantly longer than the rest of us," said Jay Olshansky, a researcher at the University of Illinois at Chicago who wasn't involved in the study.

Still, the findings add to a growing body of evidence suggesting that U.S. presidents live about as long as normal citizens, despite any advantages from their upbringing that may have helped them win the election, said Andrew Oswald, an economics researcher at the University of Warwick in the U.K. who wasn't involved in the study.

"I imagine Mr. Obama is woken more often in the middle of the night than any of us would like or could tolerate," Oswald added by email. "The runners-up are plainly not `losers' but ultimately they do not have to carry the responsibility of knowing the national buck stops with them."