National Association of School Psychologists President Stephen Brock recently stated the importance of kids getting adequate sleep. He sited this article:
Sleep for kids : http://www.sleepforkids.org/html/sheet.html
Parents.com : http://www.parents.com/health/healthy-happy-kids/why-your-kid-needs-sleep/
Lifehacker recently had a post with a parent friendly chart on when to put your kid to bed.