The average teenager actually stays up much later at night than they should and then they do not get the required amount of sleep to function properly the next day.
Most average teenagers go to sleep around 9:00 PM to 11:00 PM at night and then get up around 6:00 AM to 7:00 AM for school.
On weekends the teenager will likely sleep in to get extra sleep to make up for those lost sleep nights.
Some teenagers do get to bed at a good time and then get the required amount of sleep per night while other teens might stay up as late as 12:00 AM and even 1:00 AM
When I was a teen there would be some nights I would stay up till 1:00 AM in the morning and then have to get up at 5:00 AM to get ready for school because I needed to shower, change clothes and eat breakfast and then wait for the school bus.
I was really tired those days and always regretted staying up too late.