About to wrap up your 30s, 40s, or 50s? However arbitrary that age may be, you're probably taking stock of what you've accomplished in the past ten years. "The imminent approach of a new decade signals the end of one era and the beginning of another," writes a group of psychologists in a new paper.
All that reflection, they found, has consequences. It can lead to either adaptive or maladaptive behaviors: actions that increase meaning or ones that tend towards a "lol, nothing matters" outlook on life. It's similar to the way that the New Year brings on a slew of debauchery, diets and gym memberships.
In the adaptive behavior category, the authors looked at marathon runners. People on the brink of a big birthday—"9-enders," as the study authors call them—were much more likely to sign up to run a marathon. Those that were regular marathoners tended to run faster in their something-9 year—on average 2.3 percent faster than if they were something-7 years old.
As for maladaptive behavior, 9-enders were more likely to commit suicide. And 9-enders were more likely to be registered on a dating website that caters to people seeking an affair—nearly 20 percent more than if the ages were randomly distributed. (And, since dating websites do not verify ages, the authors also conducted a quick study to check if non-9-enders were more likely to lie about being a 9-ender than any other age. They weren't.)
"Although some of these effects were small," the authors write, "they occur in domains with consequential life outcomes." And if you're a 9-ender, the findings from another paper, on the meaning of meaning, are worth thinking about: "Satisfying one’s needs and wants increased happiness but was largely irrelevant to meaningfulness. Happiness was largely present-oriented, whereas meaningfulness involves integrating past, present, and future."