You need to do this even if you don't subscribe to the idea of work life separation. You'll find better solutions to complex problems if you can rest, exercise,

You need to do this even if you don't subscribe to the idea of work life separation. You'll find better solutions to complex problems if you can rest, exercise, pursue a hobby or other distraction for part of each day. The subconscious needs recruitment for anything non trivial. Log it and state the problem that isn't yet solved explicitly in writing. Then affirm to yourself that you will come back with a solution.