As a night person, I do the overwhelming majority of riding at night, usually after midnight. My personal experience is that it is safer than daytime riding for the simple fact that there are much fewer cars on the road, and because my lights make me more visible from a greater distance than I would be on the same roads during daylight hours. As a result, I find that I am given much wider berth by passing cars at night vs. "just enough" room during the day.
This is traffic-congested suburban Raleigh, North Carolina. Your mileage may vary.
-Bob