I am 15 years old and have to wake up

Patient: I am 15 years old and have to wake up at 6 am for highschool. My normal bedtime is 9:30, but I’ve found if I stay up until 12 am I don’t feel tired AT ALL the next day during school, which improves my work ethic. If I go to sleep around 9:30 or 10:30, I often feel worn out at school the next day. Why? Should I continue staying up until 12, getting only 6 hours of sleep?

Doctor: