Chemar, I have some papers here somewhere. I'll post them when I can find them and get them organized.

Do you have a Medscape registration?
Circadian rhythm is one of the things that really interests me. Some years ago I was looking into it a lot because there was all the research coming out about Seasonal Affective Disorder and circadian rhythms.
I have problems with sleep, but it's for different reasons from my son. I have RLS. He on the other hand most certainly has issues with circadian rhythm.
My daughter on the other hand has no problems with sleep at all other than the usual teenage-oversleeping-in-the-morning business.

Medscape Medical News
Wake Time Influences Circadian Clock More Than Bed Time
Yael Waknine

Let me know if that url doesn't work. I copied it after I logged in.

[Edited 'cause I forgot something. There is a chapter regarding "sleep" in the book, "Advances in Neurology, Volume 85, Tourette Syndrome" (edited by Cohen, Jankovic, and Goetz) which would be available at medical libraries. There is a newer one out, Volume 99 which might have more up-to-date information, I don't know.]