They say a smile can brighten the darkest day. Now researchers think it can also extend your days.

A study in the journal Psychological Science examined a database of professional baseball players and found those who put on a happy face in their official photographs — ended up living longer than those who didn't smile. Those with broad smiles lived an average of five years longer than players who didn't smile — reaching an average age of nearly 80. Those with partial smiles lived an average of 73 years.

While psychologists have found increasing evidence that a positive outlook leads to a more stable and happy life, this is the first time they have linked smile intensity with lifespan.

Psychologists say this makes sense but it doesn't necessarily mean people who don't smile a lot are facing a shorter life expectancy.

Bottom line, it’s another indication that happiness is good for your health.