Most of the important biological processes that occur in the human body during sleep depend on circadian rhythms, which in turn are very sensitive to the presence of even a little light from modern gadgets (i-pods, laptops, phones, e-books, TVs, etc.). According to this study, even minimal exposure to light from an artificial source at night negatively affects human health by changing the expression of genes that are associated with the formation of cancerous tumors, as well as anti-cancer genes.

Scattered light from streetlights, alarm clocks, and other electronics that glow throughout the night can affect your sleep, especially if they have blue light bulbs built in.

Delayed melatonin release in the body by an artificial light source directly affects human health. Our biorhythms are disrupted and the metabolic activity necessary for cellular repair goes out of whack.

Take special care of your children: they should sleep in a completely dark room, it will reduce the risk of various diseases and enhance the positive restorative effect of a good night’s sleep.

However, sleep disturbances are far from the worst consequence of an overdose of blue light. Some researchers believe that systematic exposure to even a very weak source of blue light during sleep can lead to a weakening of the immune system and thus adversely affect health. 

Melatonin Levels

The researchers measured melatonin levels under both blue and green light of different brightnesses. They found that blue light was the most effective way to affect its concentration, especially if it was bright, but the effect of green light was also able to give a response under certain circumstances. Green light has the same effect of keeping a person awake as blue light does. But this state passes more quickly, melatonin levels go up and one wants to sleep.  If you use blue light, especially bright blue light, melatonin levels decrease and do not increase for much longer periods of time. Thus, using blue light can keep you awake much longer.  In practice, this may mean that if you want to put off sleep for a while and then fall asleep soundly, green light is more appropriate. And if you plan to stay up all night, a bright blue light is better. Blue light helps people who work in shifts to adjust the “internal clock” and fall asleep normally, can improve the quality of life of firefighters, medical professionals who have to work at night.

Read also: What is a Pendant Light

red light

Red Light

If you need night lighting (night light), use red light. During World War 2, the common color of night lighting was red, which did not light up the retina during night operations and did not “kill” the vision, unlike conventional white light bulbs. With red lighting, people needed less time to adapt in the dark because their eyes were less “strained.” Red light lamps were used by aviation (night flight pilots, night flight fighters) and at security objects (especially those guarded by patrols, which fell in the shade and in the lighted place during their detour). In recent years, green light sources have been used for night operations. 

green light

Red or Green Light?

But what is better for the retina and what is less stressful for the eyes at night: red or green light?  Both colors have their pros and cons. The human eye is designed so that it is much more sensitive to green light than red. That is why by using green light at low light levels a person is able to see more than with other light sources. In other words we have better visual acuity with green lighting.  Moreover – green light also differentiates the colors of objects, separating them by individual colors. In the case of red backlighting, the retina is not always able to distinguish colors: all objects are colored about the same tone, differing only in contrast and darkness.

Thus, at low luminance levels, green light offers more advantage than red light. Night vision remains sharp, objects and objects can be seen more clearly and their contours sharper, and you can also read text or maps with greater efficiency, easily distinguishing numbers and letters. Moreover, one color can be more easily distinguished from another.

At high luminance levels, red light offers more advantages than green light, as it does not increase dark eye disadaptation as much, preserves night vision more, and reduces the time of dark adaptation. Also, red light is not as detrimental to the eye’s ability to perceive light in general.

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