Okay I genuinely need help because this is getting out of hand. My 14 year old daughter has school the next morning and every Sunday night, actually every single night before school, she is still awake at midnight doing things that have nothing to do with school. Phone, YouTube, talking to friends, anything but getting ready. She knows she has to wake up at 6:30. She knows she will be exhausted. But it still happens every time like clockwork. I have tried talking to her, taking the phone, setting alarms, nothing sticks. She is not a bad kid at all, she is actually really smart. She just cannot seem to start winding down. Does anyone else deal with this? What actually works long term? Because I am running out of ideas here 
Oh this is so familiar it hurts 
My son was doing the exact same thing last year at 15. The thing that nobody tells you is that teenagers literally have a different biological clock than adults. Their bodies naturally want to stay awake later and wake up later. So part of what you are fighting is not laziness or attitude, it is actual biology. That said, it does not mean nothing can be done. What helped us was creating a non negotiable phone off time, not taking the phone away, just an agreed time where it goes on the charger in the kitchen. Not her room, not her desk, the kitchen. Out of sight really does mean out of mind for them.
The smart kid thing you mentioned actually made me pause because that was my daughter too. Funny how the ones who totally understand the logic of why they should sleep are also the ones staying up the latest 
What I found was that logical explanations did not work because she already knew all of them. What worked was making the morning painful enough that she connected the dots herself. Not in a punishing way, but I stopped waking her up multiple times. One call, that is it. She missed the bus twice, felt awful, and suddenly started caring about bedtime in a way no conversation ever achieved. Sometimes experience teaches better than advice.
I want to bring up something a bit more practical here. A lot of teens procrastinate at night because the night is the only time that actually feels like theirs. School, activities, homework, family time, it all belongs to someone else’s schedule. Then 10pm hits and that is finally her time with zero obligations. So she stretches it. This is not a discipline problem, it is a boundaries problem. If you can find a way to give her more genuine free time earlier in the evening, like a real no obligations window, she might not feel the need to steal it from sleep. Worth thinking about before going straight to stricter rules.
Agreeing with Krytexis that the bedroom charger thing is a game changer. I would also add that having the phone in the room is like putting a plate of cookies next to someone on a diet and expecting them to just not eat them. Willpower is not the issue, the setup is. Also something that worked for us was a wind down routine that she actually helped design. Not something I handed her, something we built together. She picked the order, she picked what was in it. When kids have ownership over the plan they are way more likely to follow through because it does not feel like something being done to them.
Not to be the sarcastic one here but have you tried just telling her that sleep deprivation causes memory loss and makes you less attractive? Because apparently telling my nephew that forgetting things AND looking tired were both side effects of bad sleep did more than three years of bedtime arguments But for real, what worked in our house was just making sure the evening had something to look forward to before the wind down. Like a small routine treat, hot chocolate, a show we watched together for 20 minutes, something that marked the transition from busy evening to calm night. Give the evening a landing spot.
What NexuForge said about night time being her own time really stuck with me because I never thought of it that way and now I cannot unthink it. My daughter used to do the same thing and once I realized she was basically living for those late hours I stopped trying to cut them off and started shifting them earlier instead. We moved her free time block to right after dinner, completely protected, no chores no homework no nothing. And then the expectation was that after that block we wind down. It took a few weeks but she stopped fighting bedtime as hard because she was not losing her personal time anymore, she was just moving it.
I remember being this exact teenager and I can tell you what I wish my parents had done differently. I did not want to go to sleep because I had anxiety about the next day and staying up felt like postponing it. Not all procrastination is about fun. Sometimes it is about avoidance. The phone and YouTube were just noise to stop me from thinking about the next day. If your daughter seems anxious about school in general, even subtly, that might be worth a gentle conversation. Not a lecture, just asking how she actually feels about school without any agenda. You might be surprised what comes out.
This thread is gold honestly. Saving it for when my kids hit this age 
But I wanted to add something from a practical standpoint. Consistency matters more than the specific strategy. I have seen parents try five different approaches in two weeks and nothing sticks because the child figures out that the rules reset every few days anyway. Pick one thing, give it a genuine two to three week run, and then evaluate. Also, and this is just my experience, involving your daughter in choosing the approach like Cynerion mentioned makes her part of the solution instead of the problem. That shift alone changes the whole dynamic.
Dad of three here again and all three went through this phase at different ages. What I can tell you is there is no one size fits all answer but there are a few things that worked across all of them in different ways. First, no screens at least 45 minutes before the intended sleep time, not as a punishment, just as a house rule that applies to everyone including the parents. We all put phones away. Hard to tell a teenager to do something you are not doing yourself. Second, keeping weekends within an hour of the school schedule. The jet lag from wildly different weekend sleep times makes Sunday nights almost impossible. That one alone made a visible difference within two weeks.
Coming in late here but I think the most underrated thing in this whole conversation is just asking her what she thinks would help. Like genuinely asking with no follow up lecture, no I told you so ready to go. Just what do you think would make this easier. Teenagers shut down when they feel managed. They open up when they feel consulted. My son gave me an answer I never would have thought of on my own, he said he needed 30 minutes of absolutely nothing after dinner before he could even think about transitioning to sleep mode. No homework, no family stuff, just decompression. We gave him that and the rest of the night got smoother almost immediately