Physiological and psychological effect of light

Year: 2015

Authors: Baldanzi E.

Autors Affiliation: CNR-INO National Institute of Optics, Largo E. Fermi 6, 50125 Flrence, Italy

Abstract: The eye is the human organ devoted to vision, and for this reason, many studies were done during centuries to discover and to study its nature. For example, what are the cells of the retina involved in the formation of images, rods and cones, is well-known since the nineteenth century. Instead, it is a recent discovery that the eyes of mammals, including humans, have specialized photoreceptors that are not directly involved in the formation of images but are rather specialized in the detection of light and related to the circadian rhythm of human beings. The discovery is revolutionary because it is like to have two organs in our eye: The first is to see and the second is for non-visual responses to light. In particular, this “new photoreceptor” is a type of ganglion cell that interacts with a different part of the brain, the suprachiasmatic nucleus, compared to that one involved by rods and cones. This new finding opens important possibilities for the treatment of many diseases and problems in regulating the biological clock, such as jet lag, seasonal affective disorder (SAD) and problems at work for example during night shifts. The light therapy is frequently used today to treat these disorders, and it is producing excellent results, for example, to treat SAD. Studying the range of frequencies to which this new type of photoreceptor is sensitive, it is also possible to open important new perspectives for the psychological well-being and behavior of human beings.


KeyWords: Carbohydrate; Cortisol; Depression; Fatigue; Placebo