I have four PCs who have just reached level 4. They are an elf and a half-elf, who have darkvision, and two halflings, who do not. A significant portion of their adventuring occurs at night or in dark places. I as a DM am getting tired of adjudicating light and vision all the time. I'd like to come up with a pretense to give both the halflings goggles of night as a quest reward, so we wouldn't have to worry about having characters without darkvision anymore. Would this break game balance?