How much sleep do I need as a teen?

No < 9 hours. During the growing years a teen needs 9 or more hours of sleep per 24 hrs. Growth spurts and physically demanding activities can add to the need. Failure to keep up with the sleep requirement can show up in a variety of ways. Poor academic performance in school, sleep walking, etc. After growth stops & activities lessen, 8hrs may be adequate.
8-10 hours. You are stiill growing and sleep has something todo with energy required for that growth.