“He’s pretty athletic,” I said, watching my 3-year-old son crisscross a playground recently. My wife agreed. “But who cares if he’s sporty?” she wondered. “What’s it good for?”

That’s precisely the concern likely to bridle the minds of returning Olympians, now that the torch of the 2012 Games has expired, ending the world’s greatest ego-dream: 16-days of rapturous crowd-waving, flag-draping fluid loss.

After the buzz of Sunday’s send-off party, and the liquid lobotomy that is night life in London, Monday was a time for dry-swallowing hangover cures and packing up the Olympic village.

That makes today, Tuesday, the true start of the post-Olympic period: the athletes’ first morning in Smallville, with the time to think about their next acts. A select few (Usain Bolt, Lebron James) can expect lucrative endorsement deals and no end to the cheering crowds. But if researchers and past performers are right, most of London’s stars, whether they are retiring or just rebooting for Rio, are in for a grueling experience—a battle with the black dog likely to test them even more than their sporting rivals.

“Ordinary life is a lot different than viewing the world from the lofty vantage point of Mount Olympus,” two-time U.S. Olympian Taraje Murray-Williams wrote on his personal blog, after coming home from the judo competition in Beijing. “Nothing feels like it can ‘go back to normal.’” The Bronx native’s life in New York City was “sickeningly mundane” next to the “superhero status” of the games, “the sense of fate, destiny—[of] being part of something so big, [so] universal. You are on stage and the whole world is watching you!”

When the world moves on, Olympians come down with a condition that Murray-Williams and his former coach Rhadi Ferguson dubbed: Post-Olympic Stress Disorder, or POSD. The affliction is a given, Murray-Williams argues. “Interview Michael Phelps in a few and even he’ll have his own story to share.”

That’s a grand prediction but not an unsupported one. The afterlife of Olympic medal-winners bears out the maxim that the higher you fly, the harder you fall. After his 1976 decathlon triumph in Montreal, Bruce Jenner told a reporter that he felt “devastated by the finality of it all,” unmoored, with “no plans, nothing,” And he got off easy.

The diver Greg Louganis went from the “super-high high” of his first Olympics to an inexplicable “low low” that culminated in a suicide attempt. The Australian Shane Gould, who was also a teenager, won five swimming medals in Munich in 1972 and then suffered through two decades of depression back home. But the U.S. diver Mark Lenzi came down with perhaps the worst case of POSD. After he won gold in Barcelona in 1992, he expected to inherit Louganis’ fame only to belly-flop into a self-described diet of “burgers, burritos, and beers.” Finally, somewhere near bottom, he told a reporter he planned to sell his medal.

Leane Shapton didn’t even make the Olympics—she finished 8th in the breast stroke at the 1988 Canadian trials—and yet, as she recounts in a new memoir, she remains haunted by the sport. “I still dream of practice, of races, coaches and blurry competitors,” she writes. “I step into the water as though absent-mindedly touching a scar.” Even F. Scott Fitzgerald knew something of POSD in the 1920s when, in writing The Great Gatsby, he described a former elite athlete as “one of those men who reach such an acute limited excellence at 21 that everything afterward savors of anticlimax.”

The further one looks back, the more the POSD case studies pile up. It’s not a diagnosis found in any academic study, but related research is out there, and has been for a long time. A 1982 study of Czech Olympians found that more than 8 in 10 suffered serious substance abuse and emotional problems on the road back to regular life. By comparison American Olympians are positively stoic: only 40 percent suffer serious problems after retiring, according to a 1997 study that looked at 57 athletes across a dozen sports. A string of studies have found that former athletes in general are at greater risk of succumbing to a life of drink, drugs, blue moods, and self-harm than the population at large.

It’s easy to appreciate what’s happening here. Olympic athletes start young, giving everything to their sport, and getting everything they need in return. When that sport is gone, so is the athletes’ world. Sports psychologists describe a “mourning period.” The athletes themselves speak in terms of a void, an absence. “The air has come out of the tires,” the Canadian rower Iain Brambell said in 2008. “Without fear of being politically incorrect,” his countrymen Curt Harnett, a three-time medal-winning cyclist, added, “I would liken it to postpartum depression.”

The latest research suggests that POSD, or whatever one wants to call it, is not just an emotional change. It’s a biological one. Exercise can create a chemical high much like a drug, according to recent work by scientists at Tufts University, and when it’s removed depression and anxiety may crowd the mind.

Whatever the explanation, many countries are beginning to recognize the perils of peak athletic performance—and launching programs to help their athletes rejoin the world of couch potatoes. The British, Australian, and American Olympic committees are providing post-Games counseling to all athletes, in addition to career training—help with résumés, interview skills, applications. Nonprofit organizations and sports therapy centers, some launched by ex-Olympians themselves, provide similar services.

Which is all for the good, of course. But if given the option, I think I’d rather my son skip any chance at Olympic glory. He can end up more like Eric Idle, who, shot from a canon at Sunday’s closing ceremony, landed with his simple solution to the post-Olympic blues: “Always look on the bright side of life.”