Like Sam says it can be spooky out there...Beavers slapping their tails on the surface of the water, the prehistoric calls of great blue herons, snakes, funky noises in the dark, Bats...Bats are usually a sign of a hatch or spinner fall...lots of Caddis, Stones, Drakes, and some of the larger mayflies make there appearances at night. Hatch or no hatch, brown trout always seem to go for sculpins and minnow imitaions that push some water.
Carry at least 3 sources of light..I like those little LED flashlights that clip on to your hat, but keep your light off unless you really need it..A light on the water will usually put the fish down, plus it will spoil your night vision for ten minutes or so...Best time seems to be during low clear water periods in the heat of the summer. Water temps are up, fish metabolism is up, but they dont come out during the day due to fishing pressure, canoes, etc. Learn how to roll cast really well so you can keep your fly out of the bushes. Cheers.