Never understood the logic of turning the lights off when all medical advice and practical thinking says it takes about 30 mins for the Mk 1 human eyeball to become fully dark adapted.
Subdued lighting so you can't see the fear in each others faces as you are about to meet thy doom, sense of smell is not affected by darkness. Any night adaption is probably going to be shot by the flash of the ensuing fireball. Guess it must be so that the pax are unaware that the fan has been hit when the generators drop off line. Do you really want to be locked in a dark cabin with 100+ strangers when everything goes pear shaped?
Face it, the lights are turned out so the crew can escape undetected, after all they know the aircraft, you don't