That being said, no such mechanic exists thus far in this game. I can go from burning my retinas off while staring at my ore smelters to ravaging the underground of all it has to offer; no mushroom unpicked, no rat un-sticked. Not only should the harsh rays of the sun give you some kind of horrible UV burns that necessitates the implementation of some kind of skin cream (a suggestion for an other day), but they should also make your pupils hella small. Whereas in the dark and damp depths of the earth your pupils should expand as they seek to suck in any and all light some kind of vacuum cleaner that only sucks in light. Below is an artist's rendition of this:
What I'm really trying to get at is that some kind of scale should be implemented that is representative of your light exposure of the past 15 minutes, maybe more, that either works in your favor or against you by lowering your perception temporarily when you enter a new environment with a different intensity of light. No longer should the dwellers of the Hearthlands be able emerge from their bastions of stone to scour the surface like some kind of bizarre biological combine harvester only to retreat into the redoubts with their bounties of the earth. No longer should the dwellers of the Hearthlands be immune from the effects of man's worst enemy: Light.