Originally posted by Emopanther:

Yes, that includes the regular nightspawns which occur in the same locations which are actually wherever you may happen to be ;)
The night spawns are the dev's crafty reminder not to keep working through the night and to go to bed ;)

According to the developers, it should be a bit more dangerous in the future - I'm not sure if at night or during the day, but I like it.

The gray dwarves I have because of the bow skill gladly killed at night from the base but to watch as the fight with the skeletons is funny.

Thank you all for the answers