Toward a Definition of Circadian Light

Light is formally defined in terms of the photopic luminous efficiency function [V(λ)], but the spectral sensitivity of the human circadian system is poorly characterized by this spectral weighting function. A new definition of circadian light should be considered because of the impact that fabricated and natural light sources may have on human health and well-being. Establishment of a formal definition of circadian light could lay the foundation for a new generation of lighting professionals and better lighting standards.