**1. Introduction**

In recent years, an unprecedented technological revolution has taken place. Many of the luminaires that humans use are being replaced by new light emitting diode (LED) light sources. Unlike the luminaires that have been used until now, which had fixed and known emission spectra, the spectral composition and intensity in each range of the visible spectrum of these new LED luminaires can be made to order, even including fixed or remote electronic control systems, and can be varied as desired at any time.

It is a scientific fact that human beings have genetically evolved to perform their activities during the day and rest during the night. The evolution of the human species has occurred under periodic and relatively stable cycles of light and darkness, next to the main cycle, which is linked to the rotation of the Earth on its own axis (light–dark cycle, 24 h) and the rotation of the earth around the sun (seasons, changed daylengths as a function of latitude, annual cycle, lunar cycle). Natural selection has favored the presence of biological clocks through all lines of evolution, allowing animals to optimally benefit from these cycles [1–4].

Maintaining proper lighting cycles, with appropriate levels of light during the day and darkness at night is beneficial to the synchronization of the circadian system. It is not only the amount or type of light we are exposed to that is important, but also the time of day when that light is received. Biological rhythms persist in constant environments; the origin of such rhythms is endogenous and depends on an internal clock. They are not, by default, driven by external signals but do have the ability to become driven by several of these signals.

The increasing use of electronic equipment late at night from an early age has aroused curiosity and fear about various related consequences, especially for children and adolescents [5]. Therefore, in this review, we examine all relevant scientific and regulatory information that exists or is under development. Numerous scientific studies demonstrate the influence of light on our biorhythms, and therefore, on the moods of adolescents [6,7].

The evolution in lighting with the introduction of LED lights that can emit any wavelength at any intensity has raised concerns about what combinations of light can be received and emitted by electronic equipment and disturbing doubts about such light's consequences for the health of adolescents.

The main objective of this review is to study the different sources of artificial light that adolescents may receive and the physiological and psychological consequences of their absorption. From this general objective, the following specific objectives were developed:


The light used in the personal and educational contexts of adolescents can be harmful, so there must be an awareness of the need to implement ethical and healthy regulations related to lighting to optimize the health and performance of young people in school contexts [1,3]. It is essential to carry out a bibliographic review and a review of the current regulations in all proposed areas to successfully legislate and set limits on the emissions of new LED lights according to their uses.

Research and practice in the domain of indoor lighting design have become a relevant topic in the search for indoor environment quality. A keyword search of articles and abstracts related to these research areas was carried out through the Web of Science (Figure 1). Indoor lighting design was the keyword.

**Figure 1.** Keywords for indoor-lighting-design-related issues.
