Correct Titan, but don't worry about the net, when you turn your bedroom lights off at night see how long it takes to start distinguishing objects around the room, a bit more than a few seconds.
Dimming the lights during the day makes bugger all difference, just keeps it all standard.
Since the only lights you will see in an emergency at night are the emrg. lights, I don't see why dimming the lights for t/off is a bad thing ?