Almost half of all adolescents in the United States are sleep deprived. Why is this such a widespread problem? The authors argue in this review that besides societal pressures and schoolwork, changes in sleep regulation during puberty lead to delayed sleep and later bedtimes. This is incompatible with early school start times and other societal pressures, but delayed sleep during puberty is likely common to mammals and not just humans.
Hagenauer MH et al. Adolescent Changes in the Homeostatic and Circadian Regulation of Sleep. Dev Neurosci 2009;31:276-284.