I've personally noticed that when night time hits players log off. That was also a trend on the official servers and is not exactly anything new.
Current day / night cycle for the server is: -- Scale time of day speed
-- (0.5 | Half of real time || 1 | Real time || 4 | 4x as fast as real time || 512 | 512x as fast as real time)
-- Scale night time speed compared to day time speed
-- (0.5 | Nights are twice as long || 1 | Nights are the same time as day || 4 | Nights are 4x speed of days || 512 | Nights are 512x speed of days)
So the days are long, and the nights should be short.
Regardless, if the people playing on pipsi would like the day / night cycle modified further or even changed to a permanent day time server i'm more than happy to get this changed for you! Please reply with what you'd like to have the Day / Night cycle be on the server and we'll go from there :)