Below, the EEIA researcher explains why this subject is of so much importance to humans as well as the world of plants and animals.
The increased use of artificial lighting at night has given rise to a phenomenon known as light pollution. It is a mounting concern, and despite its scale, it is one of the least known forms of environmental pollution and few residents of highly urbanized areas are aware of its existence.
Highs and lows of artificial light
The tremendous advantages associated with light and the negative connotations of darkness lead to the situation where the pairing of two seemingly opposite concepts: pollution and light, is still baffling to many. Light is after all one of the prerequisites of life on Earth. Sunlight aids the human body in vitamin D synthesis and impacts our well-being and mood. Sunlight is also a crucial factor in plant growth, development, and physiology. Once the sun is down, at dusk, outdoor artificial lighting helps you feel safe.
In contrast, we tend to associate the word ‘pollution’ with something negative, undesirable, harmful, and threatening. Still, while concepts such as air and water pollution are already generally known and understood, many people in Poland, despite the efforts by many organizations, have yet to come across the term ‘light pollution’.
Light pollution was first recognized in a broader sense by astronomers. They noted that continued increase in artificial urban lighting was leading to increasing luminosity of the night sky, making it more difficult to observe stars and other celestial bodies.
Impact on human health
But it is not only astronomers that experience the effects of excessive lighting at night. A growing body of research implies that night-time illumination can also adversely affect human health. The disruption of the body’s natural circadian rhythm caused by artificial lighting leads to sleep problems, which may consequently bring about a range of health problems, including insomnia, stress as well as much more serious conditions such as heart disease and diabetes. Our internal biological clock is regulated by a cycle of light and darkness. Exposure to artificial light, especially in the evening and at night, can upset this natural cycle, causing a reduction in the production of melatonin, known as the hormone of darkness.
Sources of light pollution
Streetlights are among the chief sources of light pollution. Their light often sneaks into homes through the windows, illuminating them and interfering with the natural darkness essential for the body to function properly at night. Another major problem that we need to consider when discussing photopollution is exposure to light emitted by electronic devices. Smartphone displays, tablet computers, monitor screens, and TV sets emit light, the spectrum of which includes a significant component of blue light, and this is particularly detrimental to humans at nighttime.
Avoiding light pollution
Our eye has certain specialized light-sensitive cells called ipRGCs or intrinsically photosensitive retinal ganglion cells. Although they are generally do not participate in the process of vision, they play a key role in regulating our biological clocks. These cells are most sensitive to blue light. When these cells are stimulated by blue light in the evening, a signal is sent to the body that it is time for daytime activity, something that is undesirable at that time and also leads to disruptions in the circadian rhythm. Thus, it is best to avoid using devices that emit blue light at least 1 – 2 hours before bedtime.
Therefore, it is best to avoid using blue-light emitting devices at least 1-2 hours before bedtime. You can, as an alternative, use blue light filters, which many devices now offer. These filters reduce the level of blue light emissions, which can help you enjoy a healthier sleep pattern. However, some level of light exposure remains, and can interfere with melatonin production, especially if you use the devices immediately before going to sleep.
Impact on animals and plants
As in humans, light at night can disrupt circadian and diurnal rhythms in animals, affecting their behavior and their health. Many animal species rely on the natural cycle of light and darkness to regulate their behaviors, such as foraging, reproduction, and migration. Artificial lighting can interfere with these natural processes. According to scientists, artificial light may be confusing to migrating birds that navigate at night guided by starlight and moonlight. Plants, like animals, respond to day and night length: it is crucial to their growth, flowering, and seed production. Artificial light at night can disrupt these natural cycles causing plants to fail to develop normally.