Diffin, Elizabeth; Lane, Megan (2010年1月22日). “Why do Americans care about late night TV?”. BBC News. http://news.bbc.co.uk/2/hi/8450575.stm. "This diet of TV late at night is a key reason up to 40% of Americans get less than the 'recommended' seven to eight hours of sleep, according to recent research from the University of Pennsylvania."