There is no question in my mind that teens are on a different sleep cycle than small children , adults, and the elderly as well. We've always allowed both easy child and difficult child to sleep their natural cycle when they aren't on a particular work/school schedule. However, when work and school call - well, work and school call. Interestingly, they both independently slowly gear their sleep cycles around a few weeks before school starts. Our local high school changed their time schedule three years ago, and it has worked wonders. Students start their school day at 8:30AM. I think that 9:00AM would be better, but I guess working parents would complain too much about that time.
difficult child has worked his next semester schedule so he doesn't have to be in class until 9:30, which is perfect for him. This summer, though, he has to be at work at 8:45.... so no late sleeping for him!
Valerie