I don't recall any specific wording saying that low-light/dark-vision being ruined by regular light levels, but from a physilogical point of view, you cannot see in two different wavelengths at the same time. You can't stand in bright light and then see "Through" the bright light into a darkened area. All you see is dark. In the same vein, you can't see into the infrared if there's a heat source (such as a torch) because the heat source washes out everything else that isn't as hot. You cannot ignore it and see "through" it.<br/><br/>It's the eternal curse of mixed parties. Those who can see into different levels of the spectrum lost the advantage because those who couldn't had to have light to function. The options were... deal with torches and other light sources, or wonder alone several yards ahead of the party and risk hitting the big baddy all by yourself and no backup for a few seconds because they couldn't see the big bad you have to deal with.<br/><br/>As a side note, even thought I'm not sure that any of the sources state it anymore, low-light requires some level of light to function. It doesn't work in complete darkness... like sewers after dark, underground tunnels or interior rooms. Dark vision is another matter, but light tends to give you a penalty on nearly everything, so you may see in total darkness, but have real troubles everywhere else... and those others without it are pretty much screwed in your natural environment... we should of all of bought something that conferes either dark vision of Low-light vision. lol