If you ever find yourself wishing you could go back in time, that's nostalgia: It's what Don Draper called "the pain from an old wound: ... a twinge in your heart far more powerful than memory alone."

Now, science can explain why you get it — and whether that’s a good or a bad thing.

What is nostalgia?

The term was coined by Swiss physician Johannes Hoffer in 1688, and for years after that, nostalgia was considered a disorder, according to The New York Times. Hoffer called nostalgia a “neurological disease of essentially demonic cause,” the Times reported. The term comes from the Greek words for "returning" (nostos) and "pain" (algos).

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In recent years, science has delved deeper into nostalgia. What experts have found is that nostalgia isn’t a disease at all: It’s actually what makes us human.

Science elaborates

In a study conducted in 1992,  Alan Hirsch found that nostalgia is a yearning for a sanitized, idealized version of the past, analogous to what psychoanalysis refers to as a “screen memory.” 

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“[Nostalagia is] not a true recreation of the past, but rather a combination of many different memories, all integrated together,” Hirsch wrote. “And, in the process, all negative emotions [are] filtered out.”

The reason this bittersweet emotion is difficult to bear is because a nostalgic person is yearning for a past that never existed, Hirsch wrote. 

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“Nostalgia, unlike screen memory, does not relate to a specific memory, but rather to an emotional state,” Hirsch wrote. “This idealized emotional state is framed within a past era, and the yearning for the idealized emotional state manifests as an attempt to recreate that past era by reproducing activities performed then and by using symbolic representations of the past.”

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Here are the benefits of nostalgia

Even though nostalgia can be painful, it can also be a powerful antidote to boredom, loneliness, and anxiety, according to research conducted by Southampton psychology professor Constantine Sedikides, cited in The New York Times.  

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Nostalgia can even make life seem more meaningful and render death less of a frightening prospect, Sedikedis' research found. That's because when people look back at the past, they then become more optimistic or inspired for the future, the New York Times reports.

What does nostalgia look like across cultures?

After Sedikides, Tim Wildschut and other psychologists at Southampton began to study nostalgia, they found that people across the world looked back on things in the same way: “The defining features of nostalgia in England are also the defining features in Africa and South America,” Wildschut told The New York Times. 

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The subjects of nostalgic reverie were universal, the Times reported:

• Memories of friends and family members
• Holidays
• Weddings
• Songs
• Sunsets
• Lakes 

In a state of nostalgia, a person looking back often views herself as “the protagonist,” surrounded by close friends, The Times reported. 

The takeaway

Nostalgia is a normal feeling that is important to the human experience. Elite Daily sums this up in a piece that examines why we yearn for the past: “Nostalgia, like sorrow and happiness, is a universal feeling. It’s one that all races, cultures, and ages share. We all grow nostalgic for the past, even if it’s not the same one we share,” Lauren Martin wrote. 

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Martin cited research by psychology professor and author Clay Routledge of North Dakota State University: 

“Nostalgia serves a crucial existential function. It brings to mind cherished experiences that assure us we are valued people who have meaningful lives.”