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Let there be (Less) Light - The Impact of Artificial Light on Humans


Image generated with AI  18 November 2023 at 2:52 pm

Yes, we’re finally coming to the part I wanted to tell you about because most of it was new to me - not that it’s all good news. In this post we’ll talk about the impact of artificial light on humans. In the second, we’ll discuss the impact on the environment and what's being done about it.

Night Walk

 Earlier this month, I went on an interesting night walk led by a lighting expert as part of Architecture Week. Our guide took us for a stroll around the city, pointing out examples of good and bad lighting and how short the history of electric light really was in the broad sweep of human history.

 At the start he told us a little about Aboriginal Astronomy. How Aboriginal people made use of the stars in their daily lives – not as Westerners might, to guide them from place to place, but rather as an Almanac which told them what season it was – whether it was time to gather emu eggs or to move to another place. Furthermore, they didn’t use the stars themselves, but rather the spaces in between and they gave these names which reflected their universe, just as later astronomers did with the constellations.

The Impact of Artificial Light

It seems that the human race has adapted well to lights on the warm red – yellow spectrum. These mimic sunlight more closely and we are still drawn to them, just as we might once have been to firelight. What we are absolutely not accustomed to, are the very high energy lights now made possible by LEDs  and especially those in the blue spectrum, as many of our screens and much of our street lighting are – think of the lights on freeways or those used to light football grounds at night.

The Problem with Blue Light LEDs

Energy – saving though they may be and thus in widespread use,  blue light LEDs have now been shown to disrupt our circadian rhythms and are associated with diseases ranging from depression, through to various cancers, cardiovascular diseases, diabetes,  sleep disorders and obesity. If you've been feeling unaccountably blue lately, then this could be one of the reasons why.

The link between these afflictions is believed to be related to the amount of melatonin which our bodies produce. Blue light cuts it by 50% more than other types of lighting. It also has an impact on eyesight and contributes to macular degeneration.

For this reason the French have banned the sale of such products for domestic use as of January 2020 and only allow them in other settings with special precautions. It recommends that children be less exposed to blue light because they are more vulnerable. This vulnerability stems from the fact that the lenses over their retinas are not fully formed until around age 20. 

Pregnant women, the elderly, people with conditions such as epilepsy or who suffer from migraine should also avoid such lighting because of the visible or invisible fluctuations to which it is prone. The French studies also found that the various screen protectors and eye protection available, vary greatly in effectiveness and neither these nor switching light modes on iPhones protects against the effects of sleep disruption or the long - term effects on eyesight. French researchers are now looking closely at the light output of things like car headlights and children's toys.

Protecting Yourself against the Impact of LEDs, especially Blue Light

According to the French recommendations, you can protect yourself from the sleep disrupting effects of blue light by turning your devices off about two hours before bed and having none on at night. This especially applies to children and adolescents. If you must have a nightlight, keep it low and in the warm white spectrum. Much the same applies to domestic lighting generally. Keep it low, indirect and warm white. 

As far as external lighting goes, the French are also setting strict limits on what may be allowed outdoors. For example, no more than 3000 Kelvins of light will be allowed in any situation, less than 2400 within the built environment and far lower for suburban and rural settings. Kelvins are about the colour intensity of light. Light below 4000K is in the reddish spectrum whereas light above 7500 Kelvins. Is considered blue and definitely a No. There are also conditions on how lighting is to be placed and reducing the use of lights overall. We shall discuss this more next time.

While the French have been the first to introduce such guidelines about lighting, expect to see much more about this in future.