I think you're on the right track, Carnival. The canonical books of the Forgotten Realms that deal with this the most are those in the Drizzt series, but the way they describe darkvision doesn't quite fit with the PHB description of it, IIRC.<br/><br/>"Darkvision is the extraordinary ability to see with no light source at all, out to a range specified for the creature. Darkvision is black and white only (colors cannot be discerned). It does not allow characters to see anything that they could not see otherwise—invisible objects are still invisible, and illusions are still visible as what they seem to be. Likewise, darkvision subjects a creature to gaze attacks normally. The presence of light does not spoil darkvision."<br/><br/>The first sentence is key, since even a cat or an owl can't see if there's absolutely no light source. It's not a matter of having a mirrored retina or an overabundance of rods to capture all of the available light. It's magical vision that can allow the creature to see in the absence of all light.<br/><br/>So while it's magical, it certainly acts very similar to how you'd expect a cat's mirrored retina and overabundance of rods to act in low light - grayscale images (since your color-seeing cones don't work well in low light) of the world around you.<br/><br/>And the last sentence implies what Re Z L said, that having darkvision and being sensitive to bright lights are two different things. Drow and duergar have both, but non-duergar dwarves only have darkvision, not light sensitivity. But it also goes further than that. If a dwarf is standing in a well-lit room and looking across it into a dark corridor, that dwarf can see into the darkness just as well as it would if all of the lights were off.