I ride the same route as mzeffex. It's a paved rail-to-trail path with no lighting. In some places, there is light spillover from houses, etc., but in other places it's quite dark. Although I try to avoid it riding the trail after dark, due to my work schedule sometimes it is unavoidable. Creepy. I worry about dogs or other animals (along with irrational "Jason" fears). I find I tend to look over my shoulder a lot. Also, with a helmet mounted light, you can see all of the little bugs, etc. in the air that fly into your face as you ride.

In terms of speed, I find that my speed actually drops a bit, as I am worried about crashing on debris, snakes, etc.