Screen dims when light sources go offscreen

[zool]

I don't really understand the problem, what do you mean?

It's like torches and candles only emit light when they are on screen, if I'm facing a lit torch, it lights up the room. If I turn around the moment the torch goes off screen the whole room goes dark, like the torch isn't lit.

This isn't gradual dimming, as I look around a room it flashes between being lit and unlit as candles and torches go in and out of view.