Imagine if your journal could predict how long you’d live. For 180 nuns it did. (This isn’t science fiction; it’s social science!)

Researchers analyzed the nuns’ journals—which they wrote in 1930, when they were between the ages of 18 and 32—and found a link between the way they recounted their emotional experiences, and their survival later in life.

First, the researchers coded the nuns’ words as positive, negative or neutral. Then, they tracked how many positive emotion words and sentences the nuns used.

A clear trend emerged: The nuns who expressed more positive emotions in their writing lived the longest. The group that used the most positive emotion words lived up to 9.4 years longer than the group expressing the least. And using more varied positive emotion words tacked even another year onto that.

Are you running to your journal to do your own science experiment yet?