NATIONAL REPORT -- New York City is not the only place that never sleeps. The rest of the United States is following suit, and quick-service restaurants (QSRs) are capitalizing on the trend.

According to Harriet Presser, author of the book "The Economy Never Sleeps," one-fifth of all employed Americans work mostly in the evening, at night or on a regularly rotating schedule. So more and more, QSRs are staying open later or for 24 hours to meet these consumers' dining needs.

The hours of midnight to 5 a.m. are the fastest-growing segment in McDonald's Corp.'s business, The Wall Street Journal reported. Nearly 40 percent of McDonald's U.S. locations are open 24 hours a day, up from 30 percent seven years ago.

"Whether it's taking on an additional job or just working a late shift, we're seeing more people out later at night," Steve Levigne, McDonald's vice president of consumer and business insights, told the news outlet.

Burger King Holdings Inc. is also catering to the late-night trend. The fast-feeder now has several hundred restaurants around the country open 24 hours, a company spokesperson said.

And Dunkin' Donuts has doubled the number of its 24-hour restaurants in the past 10 years, according to the Journal.

"I think we really have moved to a clockless day," John Costello, chief marketing and innovation officer for Dunkin Brands Group Inc., told the newspaper. "People are working longer hours, in many cases multiple jobs, and are more time-starved that ever before and they want the flexibility to have a full variety of products that aren't limited by time of day."