Swimmer Allison Schmitt is all smiles after winning gold and silver in Rio de Janeiro, but she struggled with depression after the 2012 Games. She sought treatment and hopes her comeback will lessen the negativity surrounding mental health issues. (Harry How/Getty Images)

The morning after her 2008 Olympics ended, gymnast Shawn Johnson awoke with one gold medal, three silvers and no idea what to eat for breakfast. She had no idea when to go to bed, either.

In the weeks that followed, Johnson felt lost each day at 4 p.m., when practice had always begun. Something as basic as working out in local fitness centers proved bewildering; she’d only trained in gymnastics facilities.

“You feel really lost for a while, just trying to figure out your new routine,” Johnson, now 24, recalled during an interview in Rio, where she covered gymnastics for Yahoo Sports. “It’s a really confusing time.”

Johnson’s experience — Olympic glory built on order and discipline, followed by an Olympic crash of confusion and dismay — is hardly unusual, nor is it a new phenomenon. Each of the 11,000 athletes who competed at the Rio de Janeiro Olympics over the past two weeks endured some measure of meticulous preparation, all building to a single competition when the world’s focus is most intense. Just beyond their medals and the post-Olympic exhibition tours and commemorative cereal boxes looms a hurdle they don’t see coming: everyday life.

“I remember waking up the next day after my last competition and feeling like I had run straight into a brick wall,” Johnson recalled. “As an elite athlete, you obsess; you’re a perfectionist over your field. And when you don’t have that to devote every ounce of energy to every day, it’s hard. Any elite athlete will tell you: The transition period from the Olympics into normal life is so hard.”

Every U.S. medalist from the Rio Olympics

Athletes and experts say this applies in both the near term and years later, both to Olympic champions and those who compete once and lose, both to competitors and coaches. On Sunday night, the 17 days of the Rio Games conclude. On Monday morning, most Americans will rise and go work. The athletes will do — what, exactly? Many don’t know.

“It’s an emotional, psychological transition, and it’s very tough,” said Steven Ungerleider, a sports psychologist and author who has worked with both the International Olympic Committee and the U.S. Olympic Committee for four decades. “. . . We’re always seeing a large number of athletes who win medals, or don’t win medals, and come home, the lights are turned out, the media is gone, and they go into a state of shock because they have been up on the pedestal and this emotional high for so long. And without their training regimen and support staff, it’s a tough transition.”

Suddenly, a lot of free time

In the months leading up to the Olympics, athletes are defined by their preparation and sacrifice. Katie Ledecky put off college for a year and swam 70,000 yards each week. Jordan Burroughs began days with pre-dawn runs and seemingly infinite sets of pull-ups and push-ups before even taking to the wrestling mat for practice sessions, eschewing time with his toddler son and infant daughter. Simone Biles chose home-schooling over her friends, and any semblance of a social life, to train more than 30 hours weekly and travel for gymnastics.

All of those decisions were based on the cycle of the Olympics. The Games may enter the public’s consciousness only for 17 days every four years. For the athletes, almost by definition, they are an obsession.

“It’s almost like Christmas,” Burroughs said. “It’s like, ‘I can’t wait until Christmas, I want to open my presents early. Mom, Dad, what’d you get me? I got to see it. The presents are under the tree, let me open them.’

“But once you open them and you play with them, you realize that, man, it’s over. Now there’s 364 days until the next one. But for us, it’s over 1,000 days.”

The effort athletes exert often results in expectations both about what being an Olympian will mean and what life afterward will be like. Taraje Williams-Murray twice made the Olympic team in judo. In 2004, he was teammates with Rhadi Ferguson. In the weeks following the Beijing Games, the two wrote a post on Williams-Murray’s blog titled, “Post-Olympic Stress Disorder: The Dark Side of Going for the Gold,” which warned athletes about the perils of becoming addicted to the competition and the attention.

“You think sex is great?” they wrote. “You think gambling [and winning] is great? Driving fast cars? Sky-diving? None of that can light a candle to the thrill of that torch, to the sense of fate, destiny — being a part of something so BIG, universal. You are on stage and the WHOLE world is watching YOU.”

The reality: Many Olympic athletes must pay some out of pocket for training and travel. Williams-Murray returned to financial stresses.

“I was burdened with debt from the run, as well as student loans,” he said Saturday by email. “I had bouts with depression and often self-medicated with alcohol and marijuana.”

That isn’t a solitary story. David Boudia was 19 when he made his first Olympic team as a diver in 2008. Like with most athletes, his focus on the Games defined his existence.

“Everything I did, I did with the idea of going to the Olympics and winning,” Boudia said before the Rio Games began. “I wanted fame, the riches. I wanted the Games to be the vehicle that delivered all those things.”

Boudia expected to win a medal, maybe two. Instead, he finished 10th in the 10-meter platform event and, with a partner, fifth in the 10-meter synchronized competition. He returned home to Indiana, enrolled at Purdue University, but entered a world he couldn’t handle. He drank. He did drugs. In his book “Greater Than Gold,” released as the Rio Games opened, he revealed that he contemplated suicide.

“The Olympics didn’t fulfill me or bring me satisfaction,” Boudia said. “So for a long time, I wanted to do nothing except to stay in bed.”

The reality is that only a fraction of the competitors in any Olympics end up on the podium. Each arrives with a goal, a standard by which he or she would define success. If that goal isn’t reached, they return home to a great unknown.

“Imagine what they’re going through,” said Robert B. Andrews, a Houston-based sports-performance consultant who works with Biles, the gymnast who won five medalists here. “They put so much passion and commitment and attention and focus into this. They all have a plan for competing. Then when the plan ends, what is the next plan? How do you even begin? There is a huge sense of loss.”

But such a sense isn’t unique to competitors who don’t medal. The public troubles of U.S. freestyle skier Jeret “Speedy” Peterson began at the 2006 Turin Olympics, where he was sent home early after fighting with a friend on the street following his seventh-place finish.

Peterson, a bold competitor who invented the high-risk “Hurricane” jump, struggled with alcohol and depression following a troubled childhood in which he was sexually abused and his younger sister was killed by a drunk driver.

When Peterson won silver at the 2010 Vancouver Games, he broke down in tears. In July 2011, he committed suicide at age 29.

Adjusting to a 9-to-5 life

The USOC’s website includes a section on sports psychology that features links to 14 articles on the topic of athletic performance, offering them as helpful resources for coaching and athletes, with titles such as “A three-step formula for competition readiness,” “Routines, rituals and performing under pressure,” and “USOC Sports Psychology’s Top Ten Guiding Principles for Mental training.”

Not a single article deals with what athletes face when competition is over. This, despite the fact that athletes, coaches and sports psychologists have understood the phenomenon going back decades. In 1997, Ungerleider studied 57 Olympians in 12 sports and wrote about the need for developing ways of helping elite athletes make a successful transition to the workplace.

“The majority don’t have a game plan,” Ungerleider said. “. . . When there is not a program in place or a mentor to prepare them, many of them get depressed. Empirical data show they start drinking or taking drugs or sort of get lost if they don’t have a support system.”

The USOC now offers the “Athlete and Career Education Program” to offer counseling and help former Olympians deal with planning a career, finding a job, networking and academics. But in some ways, the very qualities that pushed these athletes to the top of their pursuits can make it difficult to fit into a 9-to-5 existence.

“Olympians are outliers, largely independent and often self-starters — individuals that are largely predisposed and may have a natural advantage as entrepreneurs,” Williams-Murray said. “The path to a new self-identity that may allow these high achievers to be happy may go beyond finding a job.”

There is now, though, a heightened awareness about what awaits Olympians when they return home. Many athletes here said they have discussed potential pitfalls with teammates. Swimmer Allison Schmitt won three gold medals, a silver and a bronze at the 2012 London Olympics, but she fell into such a deep depression over the ensuing two years that she and her coaches believed it was unlikely she would compete at such a level again.

With help, Schmitt overcame her problems. She came to Rio with the goal of not only helping the Americans to a medal — which she did, gold in the 4x200-meter freestyle relay — but to, as she said, “de-stigmatize the negativity around mental health.” Schmitt said before she left Rio that she plans to travel, that she knows she must keep busy. But she also knows that understanding her past experiences doesn’t mean she is better prepared to deal with what’s to come.

“I’m more aware of it,” she said. “I don’t know exactly how much more prepared I am for it. I would like to say I am.”

The last day of the Rio Games is Sunday. Some athletes have already departed. And back in Houston, Andrews, the sports-performance consultant, is fielding pleas for help.

“I’ve already had [Rio] Olympic athletes calling me and saying, ‘I need to come in and talk. I don’t know what to do next,’ ” Andrews said. “Their Olympics are over and, ‘I don’t know how to handle everything that’s coming at me. How do I handle this TV show and all these appearances and endorsements? I want to keep competing, but I don’t know how much time to take off. Where do I go to vacation?’ ”

Adam Kilgore contributed to this report.