*3.2. Analysis of the Possible Negative E*ff*ects of Blue Light from Electronic Devices on the Eyes of Adolescents*

The first type of cancer to be associated with the suppression of melatonin production was breast cancer in a 1987 publication by Stevens [42]. Stevens claims that the level of ambient light in the room during the sleep period is associated with other diseases such as diabetes, obesity, depression, and affective disorders, supported by multiple publications, such as Obayashi et al. (2013) [43] and McFadden et al. (2014) [44]. The authors conclude by stating that, although the light that reaches us

from the sun contains a high irradiance at all visible wavelengths, its maximum is 480 nm, which is perceived by humans as a beautiful blue (e.g., a clear day in the middle of the morning). This is the most optimal wavelength to signal to an organism that it is day rather than night [43].

Experimental and epidemiologic studies suggest that light at night (LAN) exposure disrupts circadian rhythm, and this disruption may increase breast cancer risk. Ritonia et al. (2020) [45] found no association between residential outdoor LAN and breast cancer for either measure of LAN. The authors found no association when considering interactions for menopausal status and past/current night work status. Ritonia et al. [45] are consistent with studies reporting that outdoor LAN has a small effect or no effect on breast cancer risk.

Konis et al. [46] conducted a 12-week study of 77 patients in eight dementia care facilities with the assumption that increased exposure to indoor lighting with natural light could reduce depression and other neuropsychiatric symptoms. The authors stated that they found positive results, but that these results should not be interpreted as a definitive prescription to replace existing treatments and that further studies should be carried out on the subject.

Lai et al. [47] concluded from their studies on mice that blue light is harmful; moreover, epidemiological studies on humans were found to be inconclusive regarding positive or negative effects of the use of blue-light-blocking intraocular lenses (IOLs). In an experiment conducted with 18 groups of four rats that were exposed to light between 460 and 480 nm with intensities of 0.6 and 1.5 W/m2, the authors concluded that the safe amount of time that these animals can be exposed to these irradiances is 12 h with an intensity of 0.6 W/m2 and for 4 h with an intensity of 1.5 W/m2 [48].

Roehlecke et al. [49] irradiated a culture of mouse retinal cells using blue light with a peak emission at 405 nm and an intensity of 10 W/m<sup>2</sup> and stated in their conclusions that oxidative stress was produced and reactive oxygen species (ROS) were generated. Torkaz et al. [50] (2013) stated that the retina is especially exposed to oxidative stress due to high oxygen pressure, UV exposure, and blue light promoting the generation of ROS. Nakanishi et al. [51] stated that cultured ROS cells exposed to blue LEDs with an emission peak at 470 nm and an intensity of 48 W/m<sup>2</sup> showed a significant increase in ROS occurrence.

Chamorro et al. [52] radiated human retinal pigment epithelial cells) (HRPEpiC) using blue light emitting LEDs with peak emissions at 468 nm, using green light with peak emission at 525 nm, and using red light with peak emissions at 616 nm, as well as white light, in 12 h light–dark cycles. The authors observed ROS, cell DNA damage, and apoptosis (delayed cell death).
