Determine brightness at specific point (dynamic lighting)

First’s first: THANK YOU EPIC!! UE4 is a great engine. Continue the good work!

And then i already have a question for you:

Is there a way to determine the amount of light at a specific spot/specific mesh? Think of a character with a torch/flashlight and darkness dweller mobs.
I want them to hide in the shadows and jump out on some trigger level of light shining on a adjacent floor mesh (or something like this).

Since this all is in a procedural generated levels, i dont have any beforehand knowledge, where there could be lights on the wall, where the corners are, which would be good hiding places etc.
AI will have to find dark spots on its own. The direct distance to the light(s) won’t help there tho.

I don’t mind to delve a bit into the engine itself, since parts of my game will be c++ anyway.