The lighting in an animal room must meet several needs. It must meet the animals' biological needs with regard to quantity and periodicity, and must also provide adequate illumination for daily observation and care of the animals. In addition, lighting should be sufficient to ensure safe working conditions for animal care personnel. Regular diurnal light cycles are provided by time controlled lighting systems in most facilities. Special research needs which require departures from normal light cycles can be arranged.

The Guide for the Care and Use of Animals states, "[F]or animals that have been shown to be susceptible to phototoxic retinopathy, light at the cage level should be between 130 and 325 lux" (p. 35). Because cages in close proximity to overhead lighting typically exceed 325 lux, albino rodents must not be housed on the top shelves of non- ventilated racks unless it can be determined that the light levels in the room do not exceed this limit.