Caffeine addicts, rejoice: all the coffee you're downing over the course of a day could be lengthening your lifespan. For real.

According to research published today in the New England Journal of Medicine, people who drank four or five cups of coffee a day tended to live longer than those who drank only a cup or less. The benefit was more pronounced for women, but men also stand to gain somewhat from pounding joe.

Coffee-drinking men cut their risk for death by 12 percent after four to five cups of java, according to the study, which was led by the National Institutes of Health's Neal Freedman. Women who drank the same amount had their the risk of death reduced by 16 percent.

Freedman and his team drew data from the National Institutes of Health-AARP Diet and Health Study, a 13-year assessment. They found that coffee drinkers progressively cut their risk of death the more they drank. The sweet spot appears to be between four and five cups of coffee a day -- any more than that, and the effect wears off somewhat.

There is a catch: people who drink coffee tend to die sooner than non-coffee drinkers. That's because coffee consumption is often linked with other unhealthy behaviors like smoking. So, to add the most years to your life, the next time you're down at the diner, double down on the coffee, but leave the cigarettes out of it.

Update: Although the study may offer coffee drinkers some peace of mind when it comes to their habit, it's important to remember that this is an observational study only, not a clinical trial. As Freedman told Bloomberg News, "we don't know for certain coffee is having a cause and effect," and that coffee has more than 1,000 compounds that ought to be tested.