Optimization of RGB LEDs to Better Control the Melatonin Suppression for Humans

Blue light effect on the human circadian cycle is not considered in a wide available lighting systems product on the market. The blue part of the white light received by a human act as a switch for the production of the melatonin by the pineal gland and can disrupt the sleeping period. The photopigment so called Melanopsin is responsible of transmitting the information “day or night” to the SCN (Suprachiasmatic Nucleus) and is sensitive to light at a bandwidth wavelength around 420 nm to 560 nm with a maximum sensitivity at 480 nm, meaning that a light source containing a significant proportion of blue light will stimulate this photopigment and then will suppress melatonin production. The link between the appearance of white light (warm, neutral or cold) and how it affects sleep in humans is generally misinterpreted. This is because at sunset, the spectral distribution of the sunlight contains a low amount of “melanopic light” (light spectrum for melatonin suppression for humans with a peak around 490 nm) and therefore does not cause a high melatonin suppression. Thus, it is commonly assumed that orange light does not affect the regulation of the biological clock. This applies only to sunlight, as well as, to blackbody emitters and not for all artificial lighting systems and in particular for LED (Light Emitting Diode) sources. Contrary to general accepted ideas, our results suggest that it is possible to create a combination of RGB LED components simulating warm white with high Melanopic Efficiency Factor (MEF), which involves the activation of melanopsin and, thus suppress the melatonin production.