Studies have shown that persons deprived of adequate light experience changes in their internal clocks that may lead to clinical depression. Too bright a light or overexposure to light can lead to irritability and disruptiveness. Thus, appropriate lighting improves the physical and social environment and promotes better morale, safety, and security. The courts, too, have identified lighting as one of the basic necessities of life and have stated that inadequate lighting poses a threat to the emotional and mental stability of inmates. That psychological stress of inmates can be reduced by adequate lighting, both natural and artificial, has been supported by correctional administrators who noted improved inmate behaviors and attitudes when lighting was increased. In addition, providing inmates with control over lighting has been found to reduce arguments and vandalism. Adequate lighting also increases security by eliminating shadows and blind spots and making it easier for correctional officers to view inmate activities. 3 references. 1 photograph.