My mama always said my bedtime was 9 pm every night except for fridays, where we could stay up as late as we wished. Fridays became the upside to the bedtime, the 9 o'clock bedtime slowly extended to later times as we got older. Kind of turned into a birthday present. Our bedtime was extended an hour per year once we turned 14. It's actually a perfect time for school and everything.
in my opinion if there in elementary school it should be 8:30 -9:30 middle school - 9th grade 10:30-11:00 10th grade and up any time as long as they can get them self up to go to school if not they i would give them a bed time but you are the parent i think you should pick what you think is suitable for them