Tween doesn’t go to sleep or wake up on their own

What do they think would help? They need to be engaged in the solution to the problem their sleep cycle is creating. You don't say their exact age, but my 13 yo was a very difficult person to wake up and get going in the morning. It was ruining everyone's day starting off with so much drama. (On the other hand, my 15 yo can stay up as late as he wants and gets up to his alarm before 7 without issue!) She ultimately said if she could get herself up via a new alarm clock, stationed across the room, she would be able to do it (she really hated being shaken awake by parents) - and for the most part, she has, with the problem coming if she forgets to set it in the evening but that's another executive function story. Thus leading to my question about if they are engaged in solutions. If not, can you explore your statement that you can't let them be late? My daughter has gotten a few tardies due to her own fault on some bad mornings. She hates it (although bluffs that she doesn't) and is embarrassed to walk in late, and it's a disincentive to be late. If part of what's going on is that you are the ride to school and you can't be late to work, I would suggest you start from the premise of you aren't going to be the ride to school and see what solutions or pathways emerge from that. (My kids get themselves to school, but we have deliberately picked school options that are close enough for them to do that - reduces parental stress in the AM considerably!)

We were fighting constantly over this, and honestly, though it has improved a lot I still have elevated blood pressure by the time our kid is out the door in the morning. Some suggestions:

• Work together on some "family agreements" -- lay down the non-negotiables (everyone needs a full nights sleep, you are required to attend school, on time, every day; you don't want to fight in the morning; in our house eating something is also a non-negotiable but you might be open to flexibility on that) and then ask them to name the things that they don't like, and the things they're open to trying. 
• Stack up the warnings. At least give them a 15 minute warning and probably a 3 minute warning if reading is the issue. Kids have no sense of time and if they want to finish the chapter, they just won't stop. 
• Consider using countdown timers at bedtime. I have a friend who swears by these: https://www.amazon.com/Secura-60-Minute-Mechanical-Countdown-Collapsible/dp/B07WFDZ72L/ -- I didn't wind up trying them, but for a kid who isn't actively defiant but just engrossed in a book, knowing what's coming goes a long way. 

In our house I honestly feel like we have toddler levels of bedtime routine, or maybe religious ritual levels: screens are off at 8PM, after which you have to brush teeth, bathe, do all your nightly rituals. One those are done, there's screens-off free time until 9:30. Then they set up their diffuser with whatever scent they want and get a 5-10 minute back rub/massage. Sometimes I'll lead a body scan in my gentlest ASMR voice (Peace Out is a good podcast for a child-focused ASMR body scan, if you can't lead it on your own.) This is 7 days a week -- there's no late bedtime on weekends because it throws their schedule out of whack. 

We moved all of the prompts up by 30 - 45 minutes because we clearly needed many, many reminders to shift gears. For us, video games are a bigger issue than reading (that's an understatement, kid actively refuses to read) so we try to give enough of a warning that they won't have to stop mid-round unless they start a new round when they shouldn't have. 

In the morning, we do one gentle 7AM rouse -- head scratches, a little back rub, "hey, it's time to start waking up." They have to manage to articulate some words like "Okay, I'm waking up" and we'll leave them alone. We come back at 7:15 a little more loudly -- "yoo, you actually do need to be getting out of bed now." and usually we get more whining then.  BUt they do get up and get dressed. For a while if kiddo wasn't getting out of bed we had a playlist (Paper Airplanes, Burning Down the House, I forget what else is on there) that we would blast until they got up. I would literally hang out in their room dancing until they got up. This worked for us because it helped offset my mounting rage, while also annoying the bejeezus out of the child. We had a lot of family meetings to settle on what works for us and I'm sure we'll have to pivot again at some point. 

We get an extraordinary amount of whining in the morning. I absolutely hate it, but I've accepted that my kid just needs to whine about getting out of bed, and needs some loving attention in the morning. We've made a lot of progress in pre-empting the whining with a more soothing wakeup (give them loving attention before they resort to negative behavior to get attention) and in ignoring a lot of the whining (I spend a lot of the morning saying "hmm." and "I can see that you're very cozy, but the time has come to get out of bed.")

Have you looked into seeing if they have a disrupted sleep cycle, getting them assessed to see if they have some kind of neurodivergence, health condition, etc? If so, this might inform and help you find strategies to help your kiddo be able to make progress in caring for themselves and their own schedules, or at the very least may help take some of the stress off of everyone (i.e.... it's not due to anyone's failure, you're not failing them, we are all just different sometimes!). My kids, now 10 and 14, sound exactly like your tween. We still struggle with these kinds of things, with both of them, including getting them to sleep and wake up on their own for school. Our 14-year-old has mild Dyspraxia (DCD) and some ADHD symptoms as well as some sensory processing differences, and we are now, at the suggestion of his high school after they decided to implement a 504 plan this year (he is at Berkeley High), about to look into more definitive diagnosis -- including wondering if he might actually be high-functioning on the Autism spectrum. He is incredibly intelligent, motivated to pursue his passions and interests, just otherwise often unable to consistently care for himself in the sense of personal space, organization, keeping a good sleep schedule, and more, in spite of all the things we have tried for many years, including all the things it sounds like you've tried as well. We are still working on helping him even remember to set his alarm clock. we're currently trying to help him set up some recurring reminders on his calendar and phone alarms, and have some success at times, but it is not consistent. He's not being spiteful, he is mostly a happy kid and just genuinely forgets and/or seems genuinely unable to force himself at times. Our youngest has ADHD and takes Adderall, he is also very bright and the adderall does help but he also struggles with "demand avoidance," self-esteem troubles, and with his sleep cycle just being generally shifted. With both our kids, if left to their own devices, they would be awake and happy until about 11 pm or midnight, then awake on their own by 10 or 11 am fresh as a daisy and totally happy... but this is difficult and does not work for public school day schedules of course. When we have to try to get our 10-year-old in particular to sleep early and then wake him up early, it is a nightmare and he is miserable and angry literally the entire day (and has been this way most of his life). We are actually now pulling him from his BUSD elementary school, homeschooling for this last month of the school year, and are going to try a homeschool charter school program for next year, for exactly this reason (it's a long story, and there are other factors as well including dealing with him being bullied at school, but essentially his mental health needs and just very-obviously-different sleep cycle are part of the equation for us.). Our 14-year-old loves Berkeley High and we are working hard to help him stay and thrive there, though mornings are still often hard for him. Anyway.......  ...  I mention all of this because sometimes neurodivergence, learning differences, and various health factors can be difficult to see and diagnose, especially in kids who are bright and precocious as well as otherwise seem happy and healthy, but they can affect so many things and aspects of our lives -- including sleep-wake cycles being different and/or disrupted, "demand avoidance" (this is a big one, and could be related to what you're seeing. It definitely seems to be for us, and I am just now learning more about it! Nobody mentioned it to us until now!), executive function abilities/differences/deficiencies, etc. With our youngest, sometimes using melatonin a half an hour before we WANT his bedtime to be helps him to settle somewhat, but it doesn't seem to help our 14-year-old unfortunately. It may be worth trying to see if it could help your kiddo be able to feel sleepier at night, melatonin does help some kids at least in that aspect. For now, we are just trying to keep on swimmin'. I think a big part of helping these kids is remaining positive ourselves and being willing to look at all the possibilities. You are doing great, you're doing your best, keep your spirits up, be flexible and open, and it will get better and a bit easier with time. If you are able to consider if a different school situation might be beneficial for your tween, to better align with their needs and help them while you figure out how to help them be able to better care for themselves and their own schedule, that may be something to think about. My husband and I struggled with this decision with our 10 year old, but can now see after only a couple of weeks that it was absolutely the right decision --just being able to wake up on his own by around 10 or 11am has been HUGE -- he is now happy when waking, motivated to begin our school day here at home, no more tears and outbursts, looks forward to our social outings and park playtime with friends, and he is regaining his love of learning. Every kid is different. That's where we are at now, and being willing to look into and understanding how neurodivergence affects their abilities and sleep cycles has definitely been part of the journey for our family.  I am not sure if any of this will help, but I hope that at least offering our perspective on this as a family with similar struggles may at least help you to you remain hopeful and positive. Best of luck to you, and take care.

I am sorry you're dealing with sleep issues. 

I understand hormones impact sleep cycles. Has the child always had trouble falling asleep and waking up late or has it been a fairly recent thing? The reason I ask is that I have a family member who has a delayed sleep syndrome. Life is not easy with this condition, and a lot of effort is made to help create a sleep friendly environment. No screen/devices at least 1.5 - 2 hours before the target sleep time; lighting is kept minimal and dim throughout the house in the evening, using light bulbs that do not emit blue light (they sell special night friendly bulbs); no caffeine (not even green tea or chocolate) at least 8 hours before the target sleep time; cooler temperature; luxurious bedding, etc. Sleeping in for people with this condition is not a behavioral issue. It's biological. They simply do not get sleepy until much later than most people. You cannot force sleep sadly. 

My tween child went through a period of sleep trouble (staying up later than normal). It turned out to be anxiety related. Therapy helped. A high tech alarm clock also helped. It can be programmed and has a gentle bird chirping sound and light that wake you up. The conventional alarm clock was too alarming for the kid. 

When we were at the previous school, the kid used to sleep in, not get their act together to get ready for school, and make all kinds of excuses not to go to school. Child hated school -- there was some bullying going on; kid was bored. We got a warning letter from the District for having so many late days and absences. It was miserable.  We changed school, and the child is now motivated to go to school and sometimes gets ready before me.

What is the ideal sleep and wake time for your child? Some kids do not need 10+ hours/night. My tween child usually starts getting ready for bed 8:30 - 9 PM and eventually falls asleep somewhere between 9:30 PM - 10 PM. We do not treat weekends differently, although on Friday/Sat. nights, we might be ok with staying up 30 min. later than normal occasionally. My kid's alarm clock is set for 7 AM. On most days, they get up between 6:30 - 7:30 AM, but I am the failsafe and go into the child's room around 7:30 - 7:40 AM. Once every other week or so, I do have to get the child up. I think my kid normally gets about 9 - 9.5 hours of sleep. It's rare for my kid to get full 10 hours of sleep and they haven't slept more than 10 hours for years. (I think they rarely slept that much even in younger years.) 

I agree with the other poster about the child being a part of the solution. When we were having morning routine issues, I asked the child "what do you think we can do to get out the door by 8:15 AM so that we can get to school by 8:30 AM? What are must-dos in the morning and things we could do in advance?" By the way, this conversation went much better after we switched school and the child wanted to go to school.