The lighting industry continues to explore potential benefits of lighting solutions that optimize human health. Studies indicate light has physiological effects that go beyond vision. In recent years, the industry has focused on the impact of light on the human circadian system, and how electric lighting choices thereby can affect circadian health. Mariana G. Figueiro, PhD, Professor and Light and Health Program Director at the Lighting Research Center at Rensselaer Polytechnic Institute, says there are four major factors in designing a lighting solution that optimizes circadian health.