Daniel Willingham's piece in the latest edition of the American Educator magazine: "Are Sleepy Students Learning?" systematically works through the experimental and correlational studies that address facets of this question for teens.
The rule of thumb is that adolescents need at least nine hours of sleep nightly. "Sleep pressure" (the inclination you feel to sleep the longer you haven't) and circadian rhythms are impacted by puberty, making teens less sleepy at night, less wakeful in the morning and more reliant on external cues like light and noise to feel tired. Sleep deprivation influences mood, cognition, behavior and school performance, though the effects are smaller than typically presumed and not devastating. They are, however, cumulative. Students with parent-set bedtimes sleep more during the week. Similarly, those who attend schools with later start times get more sleep and do better in school.
Willingham reviews the struggles one district (Fairfax County, Virginia) has faced in tackling this issue. Fairfax has considered moving the 7:20 am start time of its high schools eight times in the past 24 years. To get nine hours of sleep, Fairfax County high schoolers need to be asleep by around 9:30 -- hard to imagine for the typical teen. But Fairfax County hasn't been able to resolve increased transportation costs, the mismatch between parent work schedules and a later school day, and interference with athletic and after-school programs or jobs.
We know teens need more sleep than adults and are biologically disposed to stay up later. We know sleep deprivation is damaging. Is there a grand bargain here, a solution that requires compromise by students, parents, schools, employers, and communities?