Appropriate bed time - 13 year old

[NeverFastAlwaysFurious]

We go to bed at 9. Sometimes before to watch a film or doom scroll. We are up extra early. DD says she cannot possibly go to bed at this time too and has set herself a bed time of 10. However I've just heard her getting in to bed now and she was fucking about not actually in bed so could have been a midnight bedtime on a school night. She wakes up at 7 to get ready for school and it's 50/50 as to whether she is cheery or the devil. She is never spritely. I forget, at my age, whether spritely in the morning was ever actually a thing. So I've given her a stern word and said we'll have a chat tomorrow about appropriate bed times and strict rules. She has friends who go later and who go earlier.

So, 13 years old and up at 7am - when is bedtime?

Usually around 9.30. Devices downstairs.

Mine go really early compared to most. One needs loads of sleep, always has done and the other swims before school so is up before 5 am.

I do clearly remember when my DD, now in her 20's was a teenager her sociable time was my bedtime. It was gruelling for me at the time as I had a baby and a toddler up really early and during the night but it seemed to be when DD really needed me.
I was chatting to a friend with a 14 year old DD and she said her daughter is the same way.

She usually takes herself to bed between 9-9:30 on a school night, can be later on a weekend but still usually in bed around 10 if she has sport they next day. Sometimes asks to watch tv for a bit when she goes to bed but doesn’t seem to stay up for long.