In my opinion you've probably worked too long and pushed too hard in a job that doesn't let your brain shut off. I get into similar situations when I'm focusing on my writing, I get to the point that I just can't shut my brain off. I'll resort to trying to relax, but I end up reading news and doing things that just keep my brain in that point of over exertion.

I resort to physical work, it still requires me to keep my focus but it doesn't require me to think nearly as much, in fact I'll find myself zoning out completely. I hand wash dishes and it gets me into the same zone where I don't have to think for 30-minutes.

If you've got property and you'll have no work commitments I would suggest learning how to maintain your property, there's lots of physical work that will release your mind and keep you away from things (IE technology) that will keep your mind in that exhausted state.

Build a shed, you'd be surprised how difficult it is to actually get it to sit level. You'll have to work the ground, then frame it and then side the walls and shingle the roof. It can be especially daunting if you've never done this sort of work, but it may be worth it to learn because not only is there economic benefits (IE you can do the work yourself rather than pay the 6x mark up companies charge from the cost of materials for this work) but 5 years down the line when you start recognizing you're feeling a bit burnt out you could use the skills you've learnt to put up a fence or something.

Physical work also has the added benefit that it helps your diet and metabolism, both of which can contribute to that burnout feeling. I'm not saying your diet will improve, I'm saying you're likely to end up eating more protein and fat, which certainly helps me. I always get into that burn-out feeling when I start eating more carbs.