Abstract
Currently, in developed countries, nights are excessively illuminated (light at night), whereas daytime is mainly spent indoors, and thus people are exposed to much lower light intensities than under natural conditions. In spite of the positive impact of artificial light, we pay a price for the easy access to light during the night: disorganization of our circadian system or chronodisruption (CD), including perturbations in melatonin rhythm. Epidemiological studies show that CD is associated with an increased incidence of diabetes, obesity, heart disease, cognitive and affective impairment, premature aging and some types of cancer. Knowledge of retinal photoreceptors and the discovery of melanopsin in some ganglion cells demonstrate that light intensity, timing and spectrum must be considered to keep the biological clock properly entrained. Importantly, not all wavelengths of light are equally chronodisrupting. Blue light, which is particularly beneficial during the daytime, seems to be more disruptive at night, and induces the strongest melatonin inhibition. Nocturnal blue light exposure is currently increasing, due to the proliferation of energy-efficient lighting (LEDs) and electronic devices. Thus, the development of lighting systems that preserve the melatonin rhythm could reduce the health risks induced by chronodisruption. This review addresses the state of the art regarding the crosstalk between light and the circadian system.
Highlights
Light is a wave corresponding to a small part of the electromagnetic spectrum to which human eyes are responsive
In spite of the positive impact of artificial light, we pay a price for the easy access to light during the night: disorganization of our circadian system or chronodisruption (CD), including perturbations in melatonin rhythm
This review addresses the state of the art regarding the crosstalk between light and the circadian system
Summary
Light is a wave corresponding to a small part of the electromagnetic spectrum to which human eyes are responsive. In Greece, lamps made from pottery or bronze started to replace torches around 700 B.C. From that time until the nineteenth century, the most commonly used and advanced lighting tool was the wax candle [3]. With the Industrial Revolution, lighting tools and technologies experienced a tremendous process of accelerated development and improvement after the discovery of the incandescence of an energized conductor by Humphrey Davy in 1801. This process culminated in the second half of the nineteenth century, with the practical use of the incandescent light bulb developed by Joseph Swan and Thomas Alva Edison [1]. Humans have altered the natural light-dark cycle contrast, which may have serious pathophysiological repercussions [8]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
