[Question] How to spawn zombies at night?

[hbeni]

Hi, is there an config option I missed that allows to spawn more zombies at night?
I remember that with a very old version this already worked, but somehow no zeds are spawning in night time here.

Generally it would be cool if i could configure something that triggers at night, maybe a custom made "event" that handles this? What is the preferred way to implement this (if it's not just an option i missed)