Hi jac64. You posted sometime ago but I have had the exact same thing in the morning with my son since he was 13. He is 16 now. It is like he is under a general anaesthetic but able to react angrily if really pushed. He does not register any alarms including one for the deaf and a sunrise one. He us very angry and aggressive but has no memory of any interactions. I have come to believe he really does not remember.
He has had extreme difficulty falling asleep for years but has melatonin for that now. It works but unfortunately does not cure the waking problems.
I find people don’t understand the extent of this problem. It might be depression but I have had a friend with depression and her inability to get up and go was not the same as literally not being able to be woken up by anything?
I wish I had an answer! Is there anyone else out there who has experienced this? I can’t find any advice on the internet.