Yes you should always drive a bit slower at night then you would during the day because it's safer.
Also your reaction time is also slower during the night than it is during the day so it's better to drive slower at night so that you have more time to react to things on the road.
If you're driving at night things such as a deer or person could come out of nowhere which you might not see right away and need more time to stop.
I always drive at least 10 to 15 miles slower at night when possible because I've had deer jump out at me on some back roads before and hit a deer doing that before.
So when I drive at night I drive slower and even slower when I'm on those back roads versus on the main roads.