Children can graduate from a crib to a bunk bed, but they should not sleep on the upper bunk before the age of 6. According to the American Academy of Pediatricians (AAP), children younger than 6-years don’t have the coordination to climb down safely or stop themselves from falling. An estimated 14,600 children under the age of 6 were treated within 2001-2004 for bunk bed fall-related injuries.