Concentration's like a shower. You don't turn it on until you want to bathe. . . You don't walk out of the shower and leave it running. You turn it off, you turn it on. . . It has to be fresh and ready when you need it.
Quidquid luce fuit tenebris agit: but also the other way around. What we experience in dreams, so long as we experience it frequently, is in the end just as much a part of the total economy of our soul as anything we "really" experience: because of it we are richer or poorer, are sensitive to one need more or less, and are eventually guided a little by our dream-habits in broad daylight and even in the most cheerful moments occupying our waking spirit.