the Sleepless in America (American Academy of Sleep Medicine, 2014), the documentary which co-produced by the National Geographic Channel, almost forty percent of Americans get less than five hours of sleep per night. Sleep deprivation often results in depression-like symptoms. Thus we heard suggestions that we should have at least eight hours of sleep a night. In fact, the duration of sleep affected by multiple factors, such as human has different sleep needs at the different age, and according to