This is the VOA Special English Education Report.

Surveys of American teenagers find that about half of them do not get enough sleep on school nights. They get an average of sixty to ninety minutes less than experts say they need.

One reason for this deficit is biology. Experts say teens are biologically programmed to go to sleep later and wake up later than other age groups. Yet many schools start classes as early as seven in the morning.
As a result, many students go to class feeling like sixteen-year-old Danny. He plays two sports, lacrosse and football. He is an active teen -- except in the morning.