The Rock method of waking up 6 days a week, doing 30 mins of heavy cardio and then lifting weights and pull ups is the only way I've found where you can keep an insane schedule without burning out. As soon as I hit a pillow I sleep no matter what I'm thinking/worrying about, and I wake up without any back pain or other problems where before I started this routine I always woke up with little pains and stiffness. I have energy all day, and the cardio seems to help with focus.

Something else I do for sanity is on Saturdays I work in a medical lab at a local university for a few hours designing and testing algorithms. It pays a joke salary, but it's intellectually satisfying work and you get access to PhDs to leech their knowledge. This can get stressful as mistakes can blow the results and ruin their research grant but it's something I look forward to doing every week outside my usual job of just adding features and putting out fires. If you can I highly recommend looking at your local university research position pages and seeing if there are any open on the weekend or in the evenings. For some reason local students here never take these.