While some of the staying-up-lateness may be self imposed, my Google searches show that puberty brings with it a natural change in circadian rythym, which isn't

While some of the staying-up-lateness may be self imposed, my Google searches show that puberty brings with it a natural change in circadian rythym, which isn't something the teens can do much about. http://www.healthcentral.com/sleep-disorders/caregiving-270879-5.html http://www.healthcentral.com/sleep-disorders/caregiving-2708... http://www.stanford.edu/~dement/adolescent.html http://www.stanford.edu/~dement/adolescent.html