Here you can modify Darkness Event lengths and time between periods of darkness.
You can also modify the availability of ambient sounds (crows and sirens).
You can experiment with these values. You can make the darkness period almost permanent.

If you disable Enable Chance Of Fog, this whole section won't matter.
Here you can modify the fog that might occur during the periods of darkness.
You can also enable the chance of heavy fog, which is an experimental adjustment of the fog levels to make visibility even lower. This assumes that you use the new Fog System in PZ, not the legacy one.

If you disable Enable Vehicle Malfunctions, this whole section won't matter.
Here you can modify how vehicles behave during periods of darkness.
You can add a chance of malfunction while driving.
Enabling Total Vehicle Malfunctions will make cars almost useless. This is not recommended if you play with very long darkness periods.

Here you can modify zombie lore during the Darkness Event.
This whole section is only confirmed to be compatible with Random Zombies.
If you're using other mods that add special zombies (like CDDA Zombies) or customizable zombie type %, I recommended disabling this section.
You do this by disabling Update zombie lore on start of events.