Nighttime at the American Museum of Natural History — as depicted in the film “Night at the Museum,” which opens today — is full of wild fantasy. There are wax figures of Attila the Hun and Theodore Roosevelt roaming the halls, not to mention raging dinosaurs. At the world premiere of the movie Sunday night, the museum took advantage of the imaginative premise to relaunch a program that allows the public to spend a night in the museum — a program that had been on hiatus for more than 15 years.

As the star of the film, Ben Stiller, gave interviews on the red carpet, families arrived carrying pillows, sleeping bags, magnetic chess sets, and flashlights. “I think it’s a fantastic idea,” Mr. Stiller, who plays the night watchman, said. “Museums are magical places, which is something kids need to understand today, when there are so many distractions like the Internet and video games.”

The museum’s sleepovers, for children between the ages of 8 and 12, will take place once or twice a month on weekends, beginning at 5:45 p.m. and ending at 9 a.m. the following day. The itinerary includes free time, scavenger hunts, and an 11 p.m. screening of a film about dolphins. When all goes according to plan, by midnight everyone goes to sleep on standard army-issue cots arrayed under the Blue Whale in the Hall of Ocean Life.

“We were under the white part of the whale. I think my parents were more comfortable than I was. I’ve never really camped out before,” 11-year-old Catherine Walker of Brooklyn said.

The program strives for a balance of entertainment and education. “We want kids to be engaged but we don’t want to hit them over the head,” the museum’s senior director of visitor services, Brad Harris, said. “No one really has a chance to get bored. Parents are just as excited as the kids.”

In fact, dozens of adults have asked if they can sleepover without children. “The answer is no. The program is tailored to children,” Mr. Harris said.

Safety is actually better at night than during the day, Mr. Harris said. “There’s more staff per visitor and, since the streets are empty, quicker access to emergency services,” he said.

Four people stay awake to monitor the Hall of Ocean Life. Mr. Harris keeps a cot in his office, where he manages to get some sleep between 1 and 4 a.m.

The cost for the night is $79 a person, and the program is already sold out until April. But it’s not the only sleepover option in town. The New York Hall of Science offers Science Sleepovers for scout troops for $45 a person. The New York Aquarium’s Sleep in the Deep is $145 a person. The Bronx Zoo’s Overnight Safaris, offered three times during the summer, are $130 a person (dates, to be announced in February, sell out in a few days).At the Rubin Museum of Art, event planners say they will offer a second version of the sleepover held last summer, at which mountaineer Luis Benitez led a simulation of an ascent through the Himalayas to Mount Everest.

Museums outside New York have sleepovers programs — some with clever names, such as the “Roar and Snore” at the National Zoo in Washington, D.C., and “Dozin’ with the Dinos” at the Field Museum in Chicago. The American Museum of Natural History named its program after the movie, “A Night at the Museum.” But to the museum’s credit, that’s where the similarities end. There is no actor dressed up as Mr. Stiller’s character, Larry, nor are the children asked to save the museum, as he must.

The real-life sleepovers, however, have plot lines that aren’t in the movie. For example, children get to visit the planetarium. They are served an evening snack and breakfast. And they get to shop in the museum store, which opens at 7 a.m. just for them.

The museum says staff was already planning to bring back the program when they learned about the film, and the timing was serendipitous.

More intimate and expensive sleepover experiences are available too. The Bronx Zoo offers an overnight birthday party package for $4,500. FAO Schwarz offers $25,000 overnights at which actors dressed as toy soldiers and princesses greet guests, who usually defer sleep to play on the “Big” piano, sing karaoke, and shop. The American Girl Place store stays open after-hours for the price of $250 a person, including a $25 gift certificate. Organizers will coordinate accommodations at a nearby hotel for sleepovers.

Told of these options, Miss Walker, age 11, was unimpressed.”I don’t think anything can be as exciting as sleeping over at the museum,” she said.

Perhaps the most famous museum sleepover took place not in real life, but in E.L. Konigsburg’s book “From the Mixed-Up Files of Mrs. Basil Frankweiler.” In that story, the children hide out in the Metropolitan Museum of Art — notably without adult supervision. Ms. Konigsburg, who now resides in Jacksonville, Fla., has not spent the night in a museum, but if given the option, she said she would choose to do so at the Morgan Museum & Library. “I would get my hands on every Jane Austen manuscript I could,” she said in an email message last night.

The Met does hold late-night parties for college students: The next one, on May 23, will take place in the Greek and Roman galleries. Togas are the suggested attire.