15 y/o still won't go to sleep on their own

[TheHuffAndPuffALot]

It's physically killing me. They don't go to bed now until 11pm and I'm expected to sit with them while they go to sleep, which can sometimes take an hour. Then they'll get me up in the middle of the night because they need a cuddle!
I have to get up at 5.30am as it is, and I'm shattered.
They say they are scared of the dark. They have night lights and the bathroom light is left on.
They refuse any outside help.
I don't know what else to do.

Years?? Or months?

Years!!

That sounds really tough. I'd set a framework of what you can and cannot do, then enforce it e.g. if you want me to sit in with you I can do that between 9 and 10, so you need to schedule your bedtime accordingly. I always suggest this next one for toddlers who need nighttime cuddles, but you could have a mattress/airbed in your room that is made up as bed. If they need nighttime company they can creep in quietly and sleep there, but no waking you for comfort, only being in the same room.

Have they tried audiobooks? Either stories to listen to when sleep is hard or relevant self-help ones to try and improve their situation. At 15 I'd guess they spend time online which I would be wanting to eliminate as much as possible as it can't be helping. Obviously outside help is desperately needed so hopefully some good suggestions for making that happen will come along.

I'm going to try your suggestions tonight as it can't carry on this way. I've just checked my sleep stats on my watch, and I'm averaging 4 hours a night. Trouble is, it's not just the teenager, I also have 2 cats that want cuddles through the night too!