Thinking about the good old days can serve as an emotional pick-me-up when times are tough. It’s a pretty basic concept, but oddly, living in the past, or experiencing nostalgia, has been thought of as a disorder since the 17th century, according to the New York Times, "ever since the term was coined by a 17th-century Swiss physician who attributed soldiers’ mental and physical maladies to their longing to return home—nostos in Greek, and the accompanying pain, algos."
In the past decade, though, scientists have applied a more rigorous research method to understand the ups and downs of nostalgia, and have determined that there’s quite a few positive effects of nostalgic thinking—including feeling warmer on a chilly day when thinking about toastier days of yore.
Research, led by Constantine Sedikides of The University of Southampton in the U.K., has shown that nostalgia can "counteract loneliness, boredom and anxiety. It makes people more generous to strangers and more tolerant of outsiders," reports the Times. "Couples feel closer and look happier when they’re sharing nostalgic memories." Researchers acknowledge that:
Nostalgia does have its painful side — it’s a bittersweet emotion — but the net effect is to make life seem more meaningful and death less frightening. When people speak wistfully of the past, they typically become more optimistic and inspired about the future.
They’ve arrived at an understanding of the positive effects of nostalgia by examining the ways that people react to sad news, like a report about a deadly disaster. Those people often became "became more likely to wax nostalgic. And the strategy worked: They subsequently felt less depressed and less lonely."
But it can be more existential than that as well. According to psychologist Clay Routledge, nostalgia "brings to mind cherished experiences that assure us we are valued people who have meaningful lives. Some of our research shows that people who regularly engage in nostalgia are better at coping with concerns about death."
So what does this all mean practically? The first is that nostalgia’s done best when it’s less about comparing the past with the present with the conclusion that the past is better. In Routledge’s words, "'[I]f they focus on the past in an existential way—‘What has my life meant?’—then they can potentially benefit.'"
Sedikides suggests using nostalgia almost like a therapy: "If you’re not neurotic or avoidant, I think you’ll benefit by nostalgizing two or maybe three times a week […] Experience it as a prized possession."