So i've been toying with the daynight cycle and was thinking of ideas on how to make the nights more dreadful and darker while still having the day time by happier and brighter.

What would you guys do to accomplish this? Would it have to do with ambiance or the sun and sky parameters?

I ended up just blackening the ambient, sky, and sun light color. Worked like a charm, but I had to cap the ambient from getting bitch black otherwise it was just impossible to see anything.

That, pretty much. You will always need a bit of ambient, since a night is never pitch-black.

Remember that you can also set the colour of the clouds (if you would have any) in the same way . You'll probably have to darken those too during the night.

Yeah good point, I was just noticing that now.