Is a 4 day week possible? Many Western European countries have laws that legally entitle you to ask for 4 days weeks (even if they say no they can't penalise you for it) and most tech companies are open to it. Go down to 4 days and you might have more energy.

Also look into moving to a less demanding team. If you're happy with your income you don't need to work crazy hard and push yourself in work. Move to a chill team, get a 4 day week and you'll have more time and energy to do research yourself.