I like for them to start getting ready at 7(snacks, book, brush teeth etc) and then my 6 year old is in bed and usually asleep by 8. My son(10) TRIES to stay up as long as he can--using every tactic he can think of but I insist he be in bed by 9. He needs his sleep(very crabby in the morning). Prevention Magazine had this article a couple of months ago(I cut it out to save for son): children ages 2 mos-1year 14-15 hours, 1-3 years need 12-14 hours, kids 3-6 years 11-13 hours, 6-12 years need 10-11 hours, 12-18 years old need 8 1/2 -9 1/2 hours a night.