Ambient Occlusion inverts color.

Hello,
I noticed my night time lighting looked odd and bright no matter how I tweaked my Skylight/Moon.
Turns out, its the AO. It inverts color the moment it gets dark thus brightening corners instead of darkening them.
I could turn it off when it gets dark but it got me wondering why it happens in the first place.

https://s28.postimg.org/uwjekwey5/image.jpg