We’ve all felt that jab to the soul you get from driving by your old high school haunts or hearing a tune you once danced to. But why is that bittersweet sort of reminiscence so universal?
Modern neuroscientists and psychologists know that a healthy dose of nostalgia is good for you, at least if you’re recalling happy days. But there was no sweetness to cut the bitter sensation in 1688, when Johannes Hofer coined the word in his medical dissertation. A combination of the Greek words nostos, or homecoming, and algos, or pain, it was a special type of homesickness associated with soldiers fighting far-off wars—and doctors feared it could kill.
Seventeenth-century physicians like Hofer worried such thoughts depleted a patient’s “vital spirits,” draining their energy and putting health at risk, says Susan J. Matt, a professor of history at Weber State University. In the 19th century, doctors debated whether nostalgia was a disease in its own right or something that exacerbated other conditions common among troops, like dysentery. Either way, they believed it could cause irregular heartbeat, fever, and, in rare cases, death.
Our opinion of nostalgia has evolved since then, but the phenomenon still eludes understanding. “It’s a very mixed emotion,” says Frederick Barrett, a cognitive neuroscientist at Johns Hopkins University. That makes it hard to shoehorn into existing psychological theory, which typically categorizes emotions as either positive or negative. And triggers—the cars, chords, or smells that blast you into the past—are extremely personal. When one person’s trash is another’s sentimental treasure, designing a standardized study is difficult.