Sleeping beneath the stars isn’t an option in wintertime, unless you are cultivating your survivalist instincts. An alternative is to break out the sleeping bags and head for the American Museum of Natural History in New York City, where families have the option of sleeping under, for instance, an enormous blue whale. This unique after-hours opportunity (no Ben Stiller sightings are promised) includes a screening of the IMAX film “Sea Monsters: A Prehistoric Adventure” and a spooky dinosaur-fossil exploration by flashlight. It’s designed for children ages 8–12 and their caregivers. Guests sleep either in the museum’s Milstein Hall of Ocean Life, under the 94-foot-long whale; beneath famous dioramas in the Hall of North American Mammals; or among the geological formations in the Hall of Planet Earth. The program dates are Friday, Jan. 9, and Friday, Feb. 6. The sleepover runs from 5:45 p.m. to 9 a.m., and the cost is $129 per person ($119 for AMNH members). It includes the movie and the fossil exploration, an evening snack and light breakfast, cots for all participants, take-home activities, and a live-animal exhibition (seasonal). To register, call 212-769-5200 or visit www.amnh.org/sleepovers for more information. Note: all participants must register in advance, and one adult is required for every 1–3 children attending. Space is limited and sells out quickly. The museum is located on Central Park West at 79th St. In Boston, the Museum of Science likewise sponsors overnight programs, but they are limited to museum members and their families (usually held in June), or to organizations such as Girl Scouts, Cubs Scouts, schools, and youth groups. For more information on their programs, which are also in high demand, families can call the membership department at 617-589-0180, and agencies can call 617-589-0350, or email email@example.com.