Management at Dover Downs estimated that 42 percent of its $217 million gambling take in 2011 came from Marylanders and advised investors that expanded gambling in Maryland could severely curtail profits.

Many of the 500 or so patrons still at Maryland Live at 4:45 a.m. Friday congregated around the electronic versions of popular table games and pushed aside half-empty cocktail cups in favor of bottled water or coffee.

Kevin Carlson and Chris Martin, friends from Columbia, posted up at a Royal Match 21 machine and played blackjack for hours. Carlson, a recent University of Maryland graduate, expects the casino to become a popular destination for people in their 20s once table games are in place in the first quarter of 2013.

"People putting money in slots are just wasting their money," he said. "[Table] games, you can have some control and win."

The state's second-largest casino, Hollywood in Perryville, has not announced plans to stay open all day, every day, but the Cecil County facility might do so once it installs table games early next year. Ocean Downs, near Ocean City, is working on a plan for integrating table games and has not indicated whether it will request full-time operation in the near future.

Although industry experts say table games appeal to a younger crowd and encourage longer stays at the casino, Norton believes the customers using overnight hours at Maryland Live won't necessarily favor slots or table games.

"It's just going to be a cross section," he said.

Karmel, though, sees 24-hour gambling as appealing largely to poker players. "They're much more likely to get involved in a long game and keep it going."

Poker remains popular among college students, who also will be tempted by Maryland Live's ability to serve alcohol around the clock, said Joanna Franklin of the University of Maryland's center for problem gambling.

"That's a concern for us," she said. "Young people simply don't have fully developed impulse control. They're up late anyway. They're looking for things to do. They like risks. This is not a good combination."

Franklin expected the loosening of restrictions that were put in place when Maryland voters approved the introduction of slot machines in 2008. Once established in the Mid-Atlantic region, casinos have been adept at persuading state governments to match or exceed deregulation steps taken in nearby states, she said.

"It's just a matter of keeping up with the Joneses," Franklin said. "Casinos want to compete, and it's hard to stop the momentum once states see the money coming in."