ATLANTA >> It is 1 a.m., but the night is young for Dre Rosenberg, a 22-year-old clothing stylist here. Later, he will grab drinks with friends and hit the nightclubs in Atlanta’s wealthiest neighborhood, Buckhead.

But first he needs a haircut.

So Rosenberg goes to one of the few places still open at that hour: the 24-hour barbershop Anytime Cutz. “Three a.m., 4 a.m., 5 a.m.,” he said. “It’s where you find your friends before the end of your night.”

This is the barbershop that never closes. And that has made it something of a cult institution in this southern capital that relishes its fashion and night life.

With hip-hop playing softly through the speakers and a futon for taking naps, the eight-chair salon caters to elite black men. Celebrities like Shaquille O’Neal and the rapper Akon have walked past the neon “Open” sign that never turns off, even on Christmas.

Other cities are taking notice. Over the past decade, 24-hour barbershops and salons have opened in New York, London and Las Vegas. The customers are as varied as their hairstyles: parents who forgot that a child’s school photo was the next day, travelers with red-eye flights, people working two jobs, musicians and night owls.

Black barbershops are evolving to keep up with modern lifestyles and an economy that forces many clients to work unusual hours, said Dwayne Thompson, an Atlanta-based writer for Against the Grain Magazine, a quarterly publication about hair salons. “These have always been fraternal places, where men can talk about the latest and greatest topic,” he said. “This just takes that conversation into the night.”

Hair is big business in Atlanta, where self-described “celebrity barbers” promote themselves at nightclubs with glossy fliers. Every summer, the city hosts the nation’s largest African-American hair products convention, the Bronner Brothers International Hair Show. And when Chris Rock filmed “Good Hair,” his 2009 documentary about the importance of hair in black culture, he began in Atlanta, which he called “the city where all major black decisions are made.”

The man behind the 24-hour barbershop idea is Ernesto Williams, 47, a longtime hair stylist. In 2005, he and his wife at the time, Carol Lamar, opened a small shop that shared a building with a 24-hour gas station. Customers would stop for gas or beer and end up staying for a haircut.

The couple were relentless promoters. He would approach celebrities for autographs, and then praise their hair and try to turn the conversation to his barbershop. He even bought a tractor-trailer, installed barber chairs and drove to festivals to cut hair inside the vehicle.

Last year, in their divorce, Lamar took control of the store from her husband. She moved it to a larger studio space and changed the name, from Ernesto’s Cuts to Anytime Cutz. A haircut costs $20, but a $10 tip is added after 9:30 p.m.

“Everybody comes here,” said Cavario Hunter, the senior editor of Hip-Hop Weekly magazine, who was transcribing an interview at the shop one recent night. “Sometimes we don’t even text or call our friends. We just come down here to find out what’s going on tonight.”

Barbers rent their chairs, so the more hair they cut, the more money they make. There is incentive to stay all night. Many say they often work 24-hour shifts. And to owners, the only added costs are utilities. “These chairs lean back,” said one barber, Mikal Muslim, 34, who goes by the nickname “Mickey the Razor.” “You can take a nap between clients and then pop up and go back to work.”

In Las Vegas, a 24-hour barbershop operates near the airport. In New York, two 24-hour Korean beauty salons have opened in Midtown in the past five years. And there is even a shop in Augusta, Ga., which has fewer than 200,000 people. That store, Kenny’s 24 Hour Barber Service, was inspired by Atlanta’s store and serves late-night truck drivers stopping along Interstate 20.

Customers have adjusted to the concept, said the owner, Kenny Bryant, 62. “Walmart is 24 hours,” he said. “The drugstore is 24 hours. Waffle House is 24 hours. The idea of 9-to-5 is dead, even for barbers.”

© 2012 The New York Times Company