Until about a year ago I had no idea that the bodysurfing scene in Rio was so big. I discovered the rush of the waves there on my own. My late wife was Brazilian, and from 2002 to 2012 we made frequent trips to Zona Sul (Rio’s south zone). A lifelong surfer, I’d bring my board and a pair of fins, in case I wanted to mix it up. At the end of those monthlong visits I’d find that the board stayed in the bag while the fins were eternally dripping wet—I’d bodysurf two, sometimes three times a day.

“Everything starts and ends at the beach in Rio,” said Vava Ribeiro, an avid board and bodysurfer and a Rio native. “Also, by tradition we have the Candomblé goddess of the ocean, Yemanjá.” Anyone plagued by troublesome thoughts or deeds goes to the ocean to purge themselves of them. “That’s the spiritual part,” he said. “The other is that we go to parties at night, we drink, we dance, we wake up with hangovers and go straight to the ocean to wash it off. Bodysurfing is our Advil.”

Mr. Ribeiro and I were treading water side by side at a spot called Pepino. Grey clouds smeared the sky. Islands dotted the horizon. To our left, sloping to the sea, was a granite mound off which swells bounced and broke into waves. And therein lies the magic. Those same Land of the Lost-looking rocks that give Rio its most iconic landmarks—the seaside peaks of Sugarloaf, Corcovado and Two Brothers—also give us the sloshing bounce that creates the wedge-shape waves that bodysurfers favor.

A widow’s peak of a wave moved almost parallel to shore. Mr. Ribeiro turned around and swam over to it, his orange fins nearly kicking me in the face. I dunked under the pitching lip. Behind was a bigger, steeper one. I put my head down, stretched my left arm forward and flutter kicked. I less caught the wave than insinuated myself into it. It flung me along, the pulses and tremors going straight to my nervous system. The ride was short, as most bodysurfing rides are. The lip grabbed my right shoulder and ragdolled me under. My knee grazed the hard sand bottom. Then my hip. I popped up next to a smiling Mr. Ribeiro.

The next morning I met Francisca Libertad, aka Chica, at Padaria Rio Lisboa, a casual bakery/café in Leblon. Ms. Libertad told me that she is the sole woman in another bodysurf WhatsApp group called “Pontão.” “It’s like an anthropological study—about men, about humility. The group is a mixture of upper-middle-class people from Leblon and poor kids from the favela, and bodysurfing is where we meet.”

Body surfers at Diabo Beach in Rio de Janeiro. Photo: Marcio Pimenta for The Wall Street Journal

We ate pão na chapa (pan-fried toast soaked in butter) at a sidewalk table. Buff folks in workout clothes pranced past. Homeless, barefoot kids begged for change. Ms. Libertad showed me her WhatsApp feed. There were 152 messages from fellow fanatical bodysurfers. “It goes on like this all day,” she explained. “Once a month we have ‘encontro,’ where we all meet, and you get about 70 bodysurfers in the water at the same time, sometimes 10 getting the same wave. Surfers don’t like seeing each other, but we bodysurfers are exactly the opposite. We love seeing each other. We’re happy to share.”

Bodysurfing is first and foremost play. Anyone who’s ever waded into the sea and ridden the momentum of the waves is technically a bodysurfer. But the fun part is angling sideways, getting that blue-face thrill. The best place to find this in Rio is in the corners of the beaches at Leme, Diabo, Arpoador, Leblon, Pepino and Sao Conrado. Diabo is more advanced, with more rocks and currents to negotiate. Pepino is famous for filthy water.

Like freestyle dance, there are no real rights and wrongs. The biggest thing is catching the right wave. You want one that’s shaped like a wedge or a teepee—as opposed to a closeout, which looms shoreward as a long, straight wall—and you want to cut across it, parallel rather than perpendicular to shore. And you want to kick hard. Fins are not mandatory but definitely help (and they can be purchased at any surf shop). Bodysurfing champion Mark Cunningham’s tips go as follows: “Know how to swim, have a suit that’s going to stay on and kick like hell.”

FIN MEET Francisca Libertad with fellow bodysurfers at Diabo Beach. Photo: Marcio Pimenta for The Wall Street Journal

A couple of days later I met Rodrigo Bruno at Leme Beach. I’d heard a lot about Mr. Bruno—“legend,” “mayor of the Rio bodysurfing scene,” “human fish.” I found him in the water, one of two bodysurfers and about a half-dozen surfers. He caught a crystalline turquoise wave and did a corkscrew move that was the stuff of giddy dolphins.

Founder of the Facebook group “Surfe de Peito & Handsurf” (9,689 members), 53-year-old Mr. Bruno told me that bodysurfing was popular in Rio during World War II. “It was a cultural import from America. We called it jacaré. That means alligator. The bodysurfers looked like alligators.” When board surfing came to Brazil, in 1964, bodysurfers took it up, Mr. Bruno said. In the 1980s, bodysurfing resurged, only to be gutted again by boogieboarding. “Now it’s back again,” he said, “more popular than ever.”

Why? “Bodysurfing is the pure basics, just you and the wave,” said Mr. Bruno. “And it works well in Rio because it is very cheap. For a poor country, poor city, poor guys, the marriage fits together very well.”

I left Mr. Bruno to the surf and went for what had become my Rio morning ritual: a bowl of açaí blended with banana and granola and a cup of steaming coffee with hot milk. The açaí in Brazil is 500 times better than its U.S. counterpart. It’s stronger in flavor and vitality. You feel its jolt.

Post breakfast, bouncing along the swirling beachfront footpath in Copacabana, my phone pinged. “Put your fins on,” wrote Mr. Ribeiro. “Diabo is going to be pumping this afternoon!” I wrote back: “I’m in.”

“Looking good #LGA new terminal B…thrilled about the bathrooms with 20 stalls!!!” Mary Wolfe of Pittsburg, Kan., tweeted on her first trip through the new concourse, which opened Dec. 1.

Ms. Wolfe says she was shocked when she entered one of the new bathrooms in Concourse B. “It made a huge positive impression on me,” she says. That concourse houses flights for Southwest, Air Canada and American and will add United flights this summer. Fliers on other airlines will also benefit as more gates open.

Bathrooms are often the first stop at an airport for passengers. Airports say clean, uncrowded facilities that are easy to find are actually a huge factor in how well-liked an airport is, and even in whether travelers will purchase food or shop at airport stores. Bathrooms—clean or dirty—often end up in social media, too.

Bathrooms that resemble ones in four-star hotels have made a big impression on travelers at LaGuardia. A lot of design effort and money went into the restrooms. Photo: © Jeff Goldberg/Esto/LaGuardia Gateway Partners

“Who talked about airport restrooms a decade, especially two decades ago? They were kind of a utility, typically behind a wall, always undersized. They almost looked used the first week they were opened,” says George Casey, chief executive of Vantage Airport Group, a Vancouver, British Columbia, company that has helped manage or operate terminals in more than 30 airports world-wide.

Now bathroom feedback is instant, widespread and effective, and restrooms have become key satisfaction drivers. “People say, If you can’t get the restroom right, what do I need to think about for the rest of my experience?” Mr. Casey says.

Money is pouring into sinks and toilets, beyond those happy-face/sad-face satisfaction voting machines so many airports have installed.

Sinks slope toward the drain without counters that get wet and messy. The new restrooms at LaGuardia are designed to be easy to clean and efficient for travelers. Photo: Scott McCartney/The Wall Street Journal

In Atlanta, sensors installed in paper-towel, toilet-tissue, sanitizer dispensers and plumbing fixtures alert custodians through an app to outages, leaks and overflows. Los Angeles International and Atlanta have both installed some Tooshlights—red and green lights, similar to parking-garage technology, that show whether a stall is available or occupied without having to push on or peer under the door.

Detroit invested in a restroom-analytics system that tracks passenger use as well as time and duration of attendant services. It uses real-time arrival and departure data to predict bathroom traffic, especially useful when storms delay flights.

“One of the biggest issues for airports is cleanliness of bathrooms. If you’re operating over capacity, it’s a real challenge,” says Phillip Brown, executive director of the Greater Orlando Aviation Authority.

Lines are typical at the tiny restrooms in other LaGuardia terminals. The airport, which handles 30 million passengers a year, is being almost entirely rebuilt. Photo: Scott McCartney/The Wall Street Journal

Much-detested LaGuardia is working on a near-complete rebuild. The central terminal, called Terminal B, is being torn down piece-by-piece to make room for new construction, a process that will stretch out to 2022. Delta’s terminal is also getting rebuilt as it continues to operate.

Construction has left travelers with numerous headaches and deep disruption, but people keep coming. Final numbers haven’t been tallied, but LaGuardia likely topped a record 30 million passengers in 2018, according to Lysa Scully, the airport’s general manager.

“We were afraid we’d scare people away, but that hasn’t happened,” says Rick Cotton, executive director of the Port Authority of New York and New Jersey, which runs all three major New York airports.

Critics have questioned the lack of additional capacity within the $8 billion LaGuardia rebuild—there’s no plan for a new runway to reduce delays. But when you are delayed, you’ll have more food and retail options, spacious concourses with 55-foot-tall glass walls, seats with power outlets, a play area for children and bathrooms that rival those of four-star hotels.

The Port Authority and its partner in the LaGuardia rebuilding, a private consortium called LaGuardia Gateway Partners that includes Mr. Casey’s Vantage Group, operate both old and new parts of Terminal B. Executives knew bathrooms would be key to changing the airport’s reputation. So they went big, and bold.

For men, the new facility has 15 stalls and 16 urinals in 2,810 square feet, compared with a total of six stalls and six urinals in 536 square feet in the space it replaces. The women’s restroom has 31 stalls, compared with 17 in the old facility, and more than four times the space. The new concourse also will have four new family restrooms for those with small children.

New concourses at LaGuardia will have family restrooms, something lacking at the existing terminals. Photo: © Jeff Goldberg/Esto/LaGuardia Gateway Partners

“The Cadillac of airport restrooms,” declared Josh Graven of Louisville, Ky., during a recent sales trip to New York. “I drink a lot to stay hydrated when I travel, so bathrooms are important. This is impressive. Bathrooms across the nation could use this as a good benchmark.”

The design is getting a lot of attention. Instead of a countertop that typically is wet and dirty, trough-style sinks have an outer edge that slopes down toward the drain. There’s a shelf above for bags, but no countertop for puddles.

Chunks of reflective glass are embedded in the floor tile, not only making them sparkle but also making them appear cleaner than they may be. “Drips get masked by the glass, so you don’t see a trail of water someone leaves,” says Derek Thielmann, LaGuardia Gateway Partners project director for design and construction.

Stalls were designed to be easier to use and easier to clean. They’re wider, with an area to store roll-aboard bags and still swing the door open. Hooks for coats, backpacks, purses and carry-on bags are mounted on stall walls, not the back of the door—hanging heavy bags on restroom doors bends them out of alignment over time and makes them harder to close securely.

Toilets are mounted to the wall instead of the floor so cleaners can actually mop underneath them. Stall dividers are hung from the ceiling rather than bolted to the floor—easier to clean the floor that way, and there isn’t hardware to rust on the floor.

And each restroom has two entrances and a partition in the middle. If one part needs to be shut down for maintenance, only half the restroom is blocked off, not the entire facility.

“@LGAairport y’all knocked it out of the park on the new terminal,” one passenger tweeted. “Actually have more than one electrical outlet and one bathroom. It’s a new day at LGA!”

Write to Scott McCartney at middleseat@wsj.com

The phenomenon is widely practiced and promoted in the U.K. through a public-health campaign started by the charity Alcohol Change UK in 2013. More than four million people have signed on in recent years, the charity says.

The phenomenon is slowly making its way across the Atlantic.

Ms. Molnar heard about the campaign through social media and joined a U.K.-based Facebook group. Now she volunteers to promote Dry January through a program called Dryuary by the Michigan-based nonprofit Moderation Management.

“When I did my first one, I thought on Feb. 1 I would go out and drink all the drinks, and I didn’t,” she says. “I probably didn’t even have a drink for the first two weeks of February. The awareness lingers.”

Research backs that up.

Richard de Visser, a psychology professor at the University of Sussex in England, has done several studies examining Dry January.

Working with Alcohol Change UK, he surveyed 857 people who signed up to participate before and after the campaign, and again six months later. Two-thirds of the participants reported that they successfully met the challenge. He published his 2016 study in the journal Health Psychology.

A small group of participants experienced a rebound effect, drinking more than they drank before, Dr. de Visser says. But overall, at the six-month follow-up mark, participants who finished Dry January and those who quit early reported drinking fewer days a week and fewer drinks per sitting on average. (Those who finished saw greater decreases.) Both groups also reported getting drunk less.

A group of liver specialists found that abstaining from alcohol for a month improved liver function, blood pressure and markers associated with cancer. Participants also lost an average of 3.3 to 4.4 pounds, says Rajiv Jalan, a professor of hepatology at University College London and co-author on the study. (He practices Dry January himself.)

Diners toasted each other with non-alcoholic beer in London last January. Photo: Getty Images

The study was published by in the journal BMJ Open in April. It compared 94 moderate-to-heavy drinkers opting to go dry for a month and compared them with 47 control participants who drank as normal.

In another study funded by the BBC and expected to be published this year, Dr. Jalan and co-researchers assigned 20 participants to abstain from alcohol for a month and instructed 10 to continue drinking as usual.

Three weeks after the dry month, the heavier drinkers had halved their alcohol consumption, Dr. Jalan says. Those who gave up drinking for a month had better liver function, lost an average of four pounds and reported better concentration, sleep, ability to exercise and less fatigue.

Ms. Molnar says better sleep is among her favorite things about going dry every January.

“You wake up more refreshed,” she says.

Indeed, sleep experts say alcohol, despite its reputation as a sedative, has a negative effect on sleep quality. Numerous studies have demonstrated this.

A study published in 2018 in the journal JMIR Mental Health found that even one drink impaired sleep quality, as measured by the heart rate variability of more than 4,000 people.

Though alcohol can induce slow-wave sleep, the deepest phase of sleep, in the beginning of the night, it reduces it later on, says Doug Kirsch, medical director of sleep medicine at Atrium Health in Charlotte.

“After a couple of hours, people will start waking up and your sleep is more fragmented,” says Dr. Kirsch, who says alcohol can also make snoring and sleep apnea worse.

Not everyone champions the concept of Dry January.

In a 2016 issue of BMJ, two experts debated its pros and cons. Ian Hamilton, an associate professor of addiction at the University of York, took the con side.

“I think it would be better if people had regular breaks, not binge breaks,” he says.

He also notes that an abrupt withdrawal from alcohol for excessive drinkers can be life-threatening.

“Over 800 people died of alcohol withdrawal in 2016,” says George Koob, director of the National Institute on Alcohol Abuse and Alcoholism, part of the U.S. government’s National Institutes of Health. “If you’re a heavy drinker, you want to get medical help for detoxification, because it really can kill you.” Seizures or hypothermia are usually what kill people in these situations.

Still, moderate drinkers definitely benefit from consuming fewer calories when they drink less, Dr. Koob says. Alcohol itself is a significant source of calories; it also stimulates the appetite. Studies have found it causes people to eat more and to opt for unhealthy foods. “You tend to graze on chips and not necessarily carrots,” Dr. Koob says.

Carol Sabransky, a senior vice president of a management-consulting firm in Chicago, one-ups all the Dry January participants by opting for a dry December.

She’s found it gives her an edge during corporate events where alcohol is flowing.

“There are so many opportunities to socially interact with my clients during this month and they are usually in good spirits, so I want to be clearheaded and on top of my game,” Ms. Sabransky says. “It is only then that I truly realize how advantaged one is when she is not imbibed.”

Sometimes, instead of having to explain herself, she will order an alcoholic drink and pretend to sip it. “I will order something just out of peer pressure,” she says. “Once everyone starts drinking, they don’t really notice.”

Ms. Sabransky says she notices that she feels better when she’s not drinking: fewer headaches, better sleep. And she definitely enjoys the reduction in calories. “If I can eat a cookie or have a glass of wine, I am definitely going to eat the cookie,” she says.

Tonight, Ms. Sabransky plans to end her dry month and celebrate with her drink of choice: vintage Champagne.

Write to Sumathi Reddy at sumathi.reddy@wsj.com