Night flying can be disorienting, especially to a newer pilot. Flying on dark nights with overcast skies is a very close thing to instrument flying. I remember flying over northern Minnesota on such a night shortly after I got my private license, and finding myself in a 40 degree bank without realizing it. Even after 700 hours of night time, I still find uncomfortable moments when circling to a "black hole" runway at night. For the most part, though, the only way to get comfortable at night is to get the experience.
Most freight dogs have extensive night experience; a few seldom log any day time. I didn't enjoy night flying nearly as much when I flew freight for AEX, because it was always at the end of a long, exhausting day, and I was fighting sleep for my final hour over the dark Mojave. I'd listen to Art Bell on the ADF, work mental math problems, do a few steep turns, even pinch myself...anything to stay awake. I almost welcomed turbulence, thunderstorms, or icing along my route: they'd ensure I stayed alert.
I don't seem to have that problem at this company. Having an extra crewmember to talk to helps, as does having extra room to stretch and move around to keep the blood flowing. I'm usually still wide awake when we finish flying. One thing I do dislike about PM schedules is that we'll typically arrive at our layover around midnight, which puts the kibosh on going out to the bar with your crew. Even if you're not going back out until 5pm the next day, my company prohibits consuming alcohol on the same calendar day that you fly, ie starting at midnight.