Using setAperture on a mission, I added 'setAperture 0.2' to the init field of a civilian unit, enabling him to see at night. I shut down the editor and joined a multiplayer server, only to be blinded when the daylight map being played was set to the same high light levels as in the editor. After some experimenting, adding setAperture to a unit, previewing, then removing it again keeps the same light level. The only way to remove it at this point is to restart the alpha.