There’s a book by Stella O’Malley called What Your Teen Is Trying To Tell You - it’s much broader than this but I think I recall there being a bit about getting teens out of their head and into their body at times like these. (If it’s not that book it’ll be Jonathan Haidt’s Anxious Generation book).
Talking about the problems all the time is just ruminating on them.
Can you get him outside? Get him moving? If not an organised team sport, then out walking. Even better if, as @Nettleskeinssays, outside in daylight, ideally in the morning.
Bright (outdoor) morning light will help regulate his circadian clock, which will help him sleep better. And if you’re out being and doing you can’t be so easily ruminating.
Try climbing, trail running, walks to find birds. Does he have any particular interests that could be hooked to being outside.
Martial arts (look at different groups, some attract a more neurodiverse group than others), fencing, nerf events? The gym (oh weights do more for the mind than they do for the body). Music & dancing (where did all the under 18 club nights go?).
Whatever you can get him to engage with will be hard at first. And then you’ll spend a lot of time reminding him how much he enjoyed it last time because getting out/changing tasks/situations is hard. But stick with it. Eventually you’ll find something that works. (Fair warning, this bit might take months or more).