Exterior version of airlock room much brighter than interior

When hab power is off and thus the internal lights are off, there's a very visible difference between the light level of the exterior and the interior version of the airlock room, whereas it shold be practically the same. The exterior version has a rather bright indirect ablient light level coming from nowhere even when the door is closed (at night it almost feels like being brighter than outside), while the interior version is pitch black, save for the red emergency light.