Article at a Glance: 

• Humans once solely relied on sunlight to illuminate their surroundings. Natural light/dark cycles helped entrain biological rhythms. 
• The history of light, from the discovery of fire to modern LEDs, has transformed the way people live by essentially giving us more time in each day for different activities. 
• Despite the many benefits of the lighting evolution, it’s important to acknowledge that the light bulb may have a dark side: it has stolen the night sky and negatively impacted the biological rhythms of humans and biodiversity. 
• Warmer (redder) lighting is more conducive and compassionate for nighttime use because it won’t throw off circadian rhythms.

---

Artificial light has become an integral part of everyday life for people all over the world. The spread of electricity has literally transformed how we communicate, travel, work, and much more — even at nighttime. As a result, society has shifted away from the natural cycles between light and dark that our ancestors once lived by.⁽¹⁾  Keeping the lights on not only impacts human health, but studies show that this can also have sizable environmental consequences. Excessive blue-rich illumination from LEDs and fluorescents disrupts the natural rhythms of humans and biodiversity created by millions of years of the earth’s steady axial rotation.⁽²⁾  Alternatively, warmer colored light bulbs – especially at night – are more appropriate and compassionate outdoor lighting options for humans and the environment.

How Lighting Has Changed Over Time

Our earliest ancestors lived in a world where, when the sun went down, almost everyone lived in the dark.  It is estimated that between 400,000 – 1 million years ago, the discovery and use of fire by humans provided light and warmth at night. It also helped scare off predatory animals, and the smoke would have been effective in keeping insects away.⁽³⁾ Since then, artificial light has taken many forms, including but not limited to: candles made from of animal fat/wax, gas lamps, incandescent bulbs, fluorescents, and the efficient LED lights that are most used today.  

Note that fire has a very warm (reddish) color temperature that is very similar to that of a sunrise or sunset. So, starting a fire at night during primitive times would not have negatively impacted circadian rhythms or sleep.   Today’s LED and fluorescent bulbs differ significantly — for humans and biodiversity – in that they emit high amounts of short blue wavelengths of light. In humans, blue light stimulates the brain more than other light — halting melatonin production and promoting alertness. This also means that blue light can disrupt the natural rhythms of humans and biodiversity during what should be periods of [natural] darkness. 

In short, light is something that society has always needed. You can actually trace 4,000 years of economic growth through its history, but the lighting evolution has also had adverse effects  on public health and the environment⁽⁴⁾.

Why Your Lighting Matters

With the spread of electric light, the night sky is no longer filled with just natural light from the moon and stars.  In fact, artificial light (from streetlights, car headlights and office buildings, for example) causes the sky in urban areas to be six times brighter than the sky in rural locations that are only 9–20 kilometers away.⁽⁵⁾ This excessive use of artificial light is also known as light pollution. 

According to the International Dark-Sky Association (IDA), components of light pollution include: 

• Glare – excessive brightness that causes visual discomfort 
• Skyglow – brightening of the night sky over inhabited areas 
• Light trespass – light falling where it is not intended or needed 
• Clutter – bright, confusing and excessive groupings of light sources⁽⁶⁾ 

Many species of plants and animals rely on light/dark cycles to help regulate important biological functions and life cycle activities (e.g. mating, molting, migration, and blooming).

Here are just a few examples showing how artificial light can impact the world’s ecosystems: 

• Light beams (from high-rises, towers, or light houses) can throw off migratory birds that rely on the moon and stars for navigation. 
• Turtles that seek beach areas to lay their eggs now often must compete with tourism and new developments whose bright lights deter females from nesting. The lighting can also disorient newborn hatchlings away from the ocean, often putting them at greater risk of dehydration or predation.⁽⁷⁾
• When a species can no longer survive in a given area, they may experience habitat loss. 
• Nocturnal animals sleep during the day and are active at night. Light pollution radically alters their nighttime environment by turning night into day.⁽⁸⁾ 
• Light pollution can disorient insects that rely on bioluminescence or reflections of light to find food or a mate.⁽⁹⁾

How Your Lighting can be More Compassionate for Humans and the Environment

Protecting the night sky is a simple yet effective way of conserving biodiversity. Of course, complete darkness is best at night, but opting for warmer lighting is the next best thing since it supports the biological rhythms of humans, plants and animals. 

The TrueLight Luna Red™ Sunset Sleep Light Bulb has adjustable color temperature settings between 3000K (equivalent to evening dusk), and 1000K (a warm red for late at night). This specific color range, combined with built-in dimming, provides ideal light exposure for regulating circadian rhythms and helping the body wind down at night. Unlike conventional lighting solutions that emit junk light and negatively impact melatonin production, this special late-night spectrum does not emit wavelengths that lessen sleep quality.  The TrueLight Luna Red™ Sunset Sleep light bulb simulates natural, relaxing light from candles and is ideal for a variety of indoor and outdoor living spaces (e.g. bedrooms, bathrooms, hallways, nurseries, porches, decks, exterior lighting fixtures and outdoor walkways).

For those weekends when you’re out camping, having a portable and warmer light source on hand is extremely convenient and compassionate too! The TrueLight Luna Red® Nightlight + Flashlight is a motion-sensing device that minimizes brightness and emits red light only to help keep your sleep/wake cycle on track in the evenings.

In thinking about the light around your home or campsite, just remember this: 

“Light can make people feel good and bring people together, but we need to think carefully about when and where we use it.” – Christopher Kyba, a researcher at the German Research Center for Geoscience⁽¹⁰⁾

References

1. https://blog.daveasprey.com/light-dark-your-sleep-satchin-panda-part-1-466/ 
2. https://www.smithsonianmag.com/science-nature/how-cities-and-lights-drive-evolution-life-180973638/ 
3. https://time.com/5295907/discover-fire/ 
4. https://www.npr.org/2014/05/02/309040279/in-4-000-years-one-thing-hasnt-changed-it-takes-time-to-buy-light 
5. https://doi.org/10.1111/gcb.12166 
6. https://www.darksky.org/light-pollution/ 
7. https://conserveturtles.org/information-sea-turtles-threats-artificial-lighting/ 
8. https://www.darksky.org/light-pollution/wildlife/ 
9. https://www.smithsonianmag.com/smart-news/light-pollution-contributes-insect-apocalypse-180973642/ 
10. https://www.theatlantic.com/science/archive/2020/07/coronavirus-pandemic-artificial-light-satellites/613087/