In general, what people call ‘light’ refers to visible light in the light spectrum (380 to 780 nm) which can be seen with human eyes among various electromagnetic waves. Among these, blue light refers to visible light which people can see as light having a wavelength of 380 to 500 nm, that is, light having the shortest wavelengths and the strongest energy in light that reaches the retina. In particular, light having a wavelength range of 380 to 430 nm is classified as violet light in the blue light spectrum.
Little is known about effects of light with the other wavelengths (e.g., visible light) other than ultraviolet rays on the human skin, but adverse effects of blue light on the skin have been recently investigated.
As published in this regard, the article (THE JOURNAL OF BIOLOGICAL CHEMISTRY Vol. 280, No. 22, Issue of June 3, pp. 21061-21066, 2005 “Blue Light Induces Mitochondrial DNA Damage and Free Radical Production in Epithelial Cell”) reports that blue light causes damages to mitochondrial DNA of epithelial cells and generates reactive oxygen species (ROS) therein to cause cellular dysfunction, cellular aging, and oncogenesis.
Also, another article (Journal of Investigative Dermatology (2010) 130, 259 to 269 “Blue-Light Irradiation Regulates Proliferation and Differentiation in Human Skin Cells”) reports that light having a wavelength of 412 to 453 nm regulates the growth and differentiation of keratinocytes and skin-derived endothelial cells, and still another article (PLoS One. 2013 Sep. 17; 8(9)e73678 “Violet Light Down-Regulates the Expression of Specific Differentiation Markers through Rhodopsin in Normal Human Epidermal Keratinocytes”) reports that violet light (410 nm) in the blue light spectrum overexpresses mRNA of rhodopsin among photoreceptors expressed in keratinocytes of the skin to reduce the phosphorylation of cAMP responsive element-binding proteins (CREBs) and reduce mRNA expression levels of keratin-10 (K10) and keratin-1 (K1) as differentiation markers for certain horny cells, resulting in reduced differentiation of human keratinocytes and delayed recovery of damaged skin barriers.
In addition to the known effects on the skin, blue light causes sleep disorders by suppressing a secretion rate of melatonin, which induces a sleeping state, and increasing a secretion rate of serotonin, which induces a waking state, and also makes the skin look dull and gives freckles by inducing melanogenesis when it directly reaches the retinae.
Because a lot of blue light is emitted from the necessities of modern people, especially from LED displays and LED lightings such as smartphones, laptop computers, monitors, etc., the people cannot help coming in unavoidable contact with the blue light under living environments in the modern society. Therefore, there have been attempts conducted to block the blue light in many ways. Among these various attempts, however, there is neither disclosure nor teaching regarding the jade powder's effect of blocking blue light. Accordingly, the present inventors have conducted research for a long period of time, and found that jade powder has an effect of blocking blue light. Therefore, the present invention has been completed based on these facts.