There is some problem with the title of the article. It could also mean that you dont need 8 hours of sleep. Other point is the need for sleep varies with age. Babies sleep for very long time like 14 hours; old people need only 5 to 6 hours of sleep. The 8 hour sleep is for youth between 25 and 40 i think. Otherwise, very original point, I have never thought sleeping in 4-hour chunks was natural.