Riding at night can be cool. Around here, the whole world smells different, you can't judge the grade/distance of any hill, and it's pretty nice.
The hour I spent in the dark-dark at the end of my last double century was different. I was tired, it was pitch black. Cars would pass (fast) and blind the **** out of me. I was sure I was going to miss a turn. The road had a bad shoulder, which made traffic feel even closer. I'm usually cool with traffic, but combined with the dark and the fatigue, it was a long hour.