OK, in addition to showering in the dark and sitting in the shower, I also do this thing where I plug my ears with my fingers and let the water run over my head. I can’t hear anything but the water rushing over my head, from the inside. It sounds like a torrential rainstorm on a tin roof and everything else is completely blocked out. It’s zen.
If I were to combine this with the other two, my head might explode from the sheer relaxation.