For this exercise I tried something a bit personal and emotional.
My thought for motivating the light is a contrast between dread and dreaming, and the fight to stay grounded and clear at the worst of times.
I downloaded the geometry from casual-effects.com.
I painted a color key to help find a starting point. This interior, a large abandoned cathedral, is void of artificial light sources, the only exception being the color cast through the stained glass windows (at least in my version). I imagine fire surrounds the first floor, no easy escape. One looks beyond convention and themselves to survive.