Schools want to improve student performance, 1 they may be stopping them from learning. Teenagers need 8.25 to 9.5 hours of sleep per night. But, most are not getting that much. 3 students study hard, they are too tired to learn effectively.Teenagers may go to bed early,4 they have problems falling asleep Teenagers should naturally wake up after 8. 5 , schools start earlier than that.Unfortunately, 6 the evidence for starting lessons later is strong, many schools will not do it.