They rarely get that much due to early school start time, inability to fall asleep until late at night, work, social life and homework. Parents may need to adjust their child's schedule to allow more sleep. Ultimately they should go to bed and wake up at the same time. Sleep deprivation can impair memory and inhibit creativity making it difficult for sleep deprived students to learn. Irritability, lack of self confidence and mood swings are often common in a teen, but sleep deprivation makes it worse.
Depression can result from chronic sleep deprivation.
Not enough sleep can endanger their immune system and make them more suceptible to serious illnesses. Judgement can be impaired. We don't know how many car crashes involving teen drivers are sleep related, but it is certainly a safety risk. Monitor your child's activities. Along with school, teens often play sports, take specialized lessons in the arts, work part time, attend school functions and clubs and spend time with their friends.