@IllForTooLong
Ok let me get that straight.
My teenage dcs wouod also do that IF I had ever let them go to bed at stupid times.
As it happens they dont so can get up like anyone else at a decent time.
He xoesnt have any medical condition. It's also nt being a teenager. its refusing to go to bed at a decent time so he is actually able to get up the morning. Until he learns that he has to get up wo any assitance and that being late/not gwetting up means crap consequences, he wont change (He is also likely to carry on as an adult with all the tales you read on here of men who play games until 3.00am and are then unable to look after their dcs/get up in the am etc...)
@IllForTooLong you don't know that, and I think it's really unwise to be so dismissive.
The OP's DS may or may not have a sleep disorder, but if he does, standard sleep advice simply does not work a lot of the time. If he has a circadian rhythm disorder (which I hope he doesn't, but feel is worth exploring), going to sleep/waking up at certain times is hardwired to an extent, and external sleep/wake cues don't wholly solve the problem, because however tired the body is, the body is hollering that it's not time to go to sleep/wake up when everyone else is doing so.
I'm 53 and I've had delayed sleep phase disorder all my life. I can be bone tired, practically dropping on the floor from exhaustion, in fact during the work week I frequently am. I go to bed about 9 p.m. most evenings, and regardless how tired I am/how active I have been/how early I got up, it's a rare evening that sees me asleep before 1 a.m. at the earliest. Normally between 2 and 3. And I get up around 7 most weekdays by necessity.
But if they had low iron levels, thyroid issues and whatnot, they would ALSO be so tired in the evening that they would in bed at a decent time.
If he does have a sleep disorder then it's not necessarily as straightforward as that, for the reasons I explained above. He could be exhausted and still be unable to sleep. Standard sleep advice that works for normal sleepers doesn't tend to make much difference if someone has a CRD.
OP I'm in no way assuming your DS has a sleep disorder, they're pretty rare and I hope he doesn't. It's a frustrating thing to have because there's not a lot that can be done to ease them. But if it's not something you've ever looked into before, I think it might be worth it. This bit of your opening post in particular is why I think so:
You can have a conversation with him that he swears later he doesn’t remember, and of course after that conversation he falls right back to sleep. Or sometimes I will ask him to repeat something I’ve just said and he comes back with gibberish.
This is me most mornings, without the falling back to sleep part, unless it's the weekend. lol In fact, DH knows not to tell me anything he needs me to remember until I am fully awake, because the chances are I'll forget it.
Circadian rhythm disorders are extremely under-diagnosed by GPs - they are rare, so I don't think much space is allocated to them in GP training. I've been fobbed off by GPs who don't know I had a formal diagnosis of DSPD from a sleep clinic in 2002. Told sleep is just a 'mindset', that it's psychological, that they just need a better bedtime routine or whatever. For some/many people this will of course be true, but not all, and I wouldn't necessarily take a GP's word as gospel on this subject.
IMHO it's statistically more likely he's just a night owl (or possibly needs his thyroid tweaking) than has anything like DSPD, but I hope my thoughts are of some help either way.