The assumption is that the teenagers are falling asleep because they are bored or disinterested in the class. Was elementary school more exciting than high school? No, that is not the reason. It is a misconception that boredom causes sleepiness. Boredom just unmasks sleep deprivation.
Sleep is essential for students to achieve their academic potential. Not only does a good night sleep prepare us for an active day of learning, it is during sleep that memories are reinforced and learning is consolidated.