The lighting that affects human biological rhythms which was mentioned briefly in the previous post is generally referred to as “circadian lighting.” The word “circadian” originating from the Latin words “circa” meaning “approximately” and “diem” meaning “a day.”

Many people have experienced feeling refreshed by the morning sun, whereas feeling sleepy in a darkened room. The biological function of adjusting circadian rhythms through exposure to sunlight continues to occur in the human body today, even after millions of years of evolution. Getting sunlight in the morning is crucial to human health, it helps us not only to wake up feeling energized, but also boosts the immune system and secretes serotonin, which is one of the “happy hormones.” At night, melatonin, a sleep hormone derived from serotonin, is produced, and helps promote sleep. In these many ways, the sunlight and human biological functions are closely linked. It is known that Florence Nightingale, a great English nurse, took hospitalized patients out for morning walks. She must have known from experience that exercising their bodies under the morning sun may help them recover from illnesses and injuries sooner.

A typical example of HCL (human centric lighting) is circadian lighting. Circadian lighting that is currently marketed is to use cool white for the morning and daytime, which is considered to be suitable for work purposes, and to use warm white for the evening, which relaxes the human mind and body. However, those colors alone are not sufficient for circadian lighting to affect biological rhythms. It is the azure-colored (sky blue) light around 480nm, which is abundant in the morning sunlight, and helps people wake up refreshed and sleep smoothly through the production of hormones. However, this part of the lighting spectrum has rarely been included in LED lights since its wavelength contributes only a little to the luminous efficiency of LEDs.

To truly have lighting that affects human biological rhythms, it is necessary to develop LEDs that emit more of this azure-colored light. Nichia's Vitasolis™ solves that problem by giving light at a wavelength of 480nm with completely the same luminous color as ordinary white lights (2700K to 6500K). However, too much exposure to this light in the late afternoon may cause difficulty sleeping due to an overproduction of serotonin, which slows down the production of melatonin. For this reason, Nichia proposes a variety of combinations to suit different purposes: Vitasolis™ at 6500K in the daytime and the regular light at 2700K excluding 480nm in the evening, or for places such as offices where color change would be less desirable, Vitasolis™ in the daytime and the other regular lights with the same color as Vitasolis™ in the evening.
Nichia's another innovation, Dynasolis™, which further pursues the features of Vitasolis™, is lighting solution that is color/spectrum adjustable by using a combination of azure and warm white colored LEDs. One of the ways to utilize this solution is to turn on the azure-colored light upon awakening, spending the morning under the high CCT light that contains plenty of 480nm, and then gradually shifting to the warm white in the afternoon – it makes people feel as if they are in the warm sunshine even in a room. This lighting solution has already received high acclaim from many of Nichia's valued customers.
Nichia hopes that the trend of the lighting market will change to a more human-friendly direction by using such unique technologies as Vitasolis™ and Dynasolis™ that will be beneficial to the human body and enhance our daily lives. For example, for those who only have limited access to the sunlight, such as people working night shifts or living in high latitudes, or for those who have difficulty maintaining a circadian rhythm due to other reasons, Nichia sincerely hopes that its products will help them achieve more vitality and satisfaction in their daily life by helping to tune their circadian rhythm.

Nichia will continue to develop LEDs that illuminate spaces brightly with less energy and support human health and happiness.

In the next post, Nichia would like to introduce LEDs that support people's sense of sight.

For more information about the products, refer to Nichia's website.
Vitasolis™
Dynasolis™