Student at the Hebrew University of Jerusalem, B.Sc. Zoology & Genetics, M.Sc. in Zoogeography, Ph.D. in Environmental Physiology and Post Doc Ecophysiology and Chronobiology, Mammal Research Institute, University of Pretoria South Africa. Since 1976 is a staff member at the University of Haifa. A full professor (Emeritus) at the Departments of Evolutionary and Environmental Biology (training M.Sc. and Ph.D. students and advising post docs) at the University of Haifa. He established the interdisciplinary Department of Natural Resources and Environmental Management (NREM) acted as the head of this department in the years 2000-2001 and 2010 -2014 in which he trains and supervises M.A. and Ph.D. students. Since May 2010, he is the head of a research center at the University of Haifa, The Israeli Center for Interdisciplinary Research in Chronobiology. Dean of faculty of Natural Sciences between the years 2002-2007. Together with colleagues and students from NREM, he studied various aspects environmental studies as light pollution and ecological footprint. Throughout his academic carrier together with his supervisors, colleagues has published over 180 papers in different previewed journal. Together with Prof. Portnov published a book: Light pollution as a New Risk Factor for Human Breast and prostate Cancers, Springer 2013.
Light as a Major Signal for the Entrainment of the Biological Clock – Exposure to Light at Night and Increasing Health Risks
The Israeli Center for Interdisciplinary Research in Chronobiology, University of Haifa, Mount Carmel, Haifa 3498838, Israel
The evolution of organisms on our plant took place under light/dark cycles, emerging from the rotation of our plant on its axis. Light within a 24h cycle, changes not only by its intensity but also by the dominant wavelength. The “Biological clock” of terrestrial plants and animals are entrained by such cycles where daytime is characterized by blue light, approximately 450-500nm with high intensities and night by long wavelength 560nm and above at low intensities. Humans as diurnal creatures looked for ways to increase hours of activity by chasing darkness away, no doubt that the development of the electrical illumination by Edison changed our life style forever. If in the beginning the light used emerged from energetically inefficient incandescent bulbs, in the last decays the move was to energy saving bulbs as florescent and recently the move towards light emitting dudes (LED) in out and indoor spaces which contain a dominant blue wavelength. So, what is the environmental problem?
Actually, from energy saving illumination we face a double problem: due to a rebound effect, we increase the light intensity at nighttime thus increasing levels of light pollution and the exposure to blue light at night. In regards to the latter, blue light of the spectrum is efficient in suppressing melatonin production in the pineal gland, but in this case, suppression will be during the dark part of the 24h cycle, when under normal dark conditions, melatonin should be produced at high levels. Among other functions, it signals the dark period to body cells. Melatonin effects different systems and functions and therefore, its suppression will result in the increase of health risk, for instance in regards to breast and prostate cancers, metabolic disorders as obesity and malfunction of the immune system. As we will go on using light at night, it should be sustainable and not only energy efficient. This should be a new challenge for illumination developers and decision-makers in regards to securing public health.