The didgeridoo, developed by the Australian Aborigines, is perhaps the world’s oldest wind instrument. Though the exact age of the didgeridoo is unknown, studies of rock art in northern Australia suggest that the Aboriginal people have been using it for approximately 1,500 years. Didgeridoos measure about 4 ft (1.5 m) in length and are made from branches that have been hollowed out by termites. A 2005 study found that practicing the didgeridoo can help reduce what sleep-related conditions? Discuss