Abstract
Some effects of light are, like vision, initiated by responses of specialized photoreceptor cells in the retina.The photic input is transduced to nerve impulses which, instead of travelling to visual centers in the brain, terminate in brain regions that control glandular function. Other biologic effects of light result from direct of photic energy on the skin and the subcutaneous tissues. This report will summarize the former, neurocondocrine effects of light, and will comment on the latter. The implications of these biologic consequences of light for the design of artificial light sources will be considered.