In our everyday lives, we are surrounded by a myriad of different light sources. Perhaps we start our day cycling to work in the rays of the sun, only to spend our workday indoors under the glow of artificial lights. But what exactly is the difference between these various light sources?
The main distinction between natural and artificial light lies in their sources. Natural light, as the name suggests, comes from a natural source, while artificial light is generated from an electrical source. One can also differentiate between the two types by considering the level of control one has over the intensity of the light source. While artificial light allows for full control through adjustments and on/off switches, natural light cannot be controlled – or can it? In fact, a campfire meets the definition of natural light, despite our ability to adjust the duration and brightness of the fire's light, which is not possible with the ultimate light source: the Sun.
Colour Distribution and Brightness
Both the sun's rays and artificial light emit light in all the colours of the rainbow, but the distribution of colours in artificial light is very different from sunlight. Sunlight has a more even colour distribution, which is what our eyes have evolved to perceive as natural. Additionally, natural and artificial light also differ in terms of brightness, which is measured in lux. On a clear summer day at the beach, the light can reach up to 100,000 lux, while it is often only around 500 lux at a workstation and 50 lux in a living room. Sunlight also emits light such as heat radiation, called infrared rays (IR), and ultraviolet rays (UV), which cannot be seen by the naked eye but can be seen on our skin, which can turn brown or red if we spend enough time in the sun.
The Key Distinctions
The distinction between natural light and artificial light primarily lies in the origin and properties of the light. Here are some of the key differences:
- Origin: Natural light originates from the sun and is spread without any human intervention. The Earth's position and rotation determine when there is light and darkness, just as the cloud cover determines how much light and which colours reach us. On the other hand, artificial light is created by humans using various technologies such as incandescent bulbs, fluorescent tubes, LED lights, etc.
- Colour Spectrum: Natural light encompasses a broad spectrum of colours ranging from violet and blue to orange and red. On the other hand, artificial light sources can exhibit different spectra depending on the technology and design of the light source, but most of them have a colour distribution that is quite different from natural light. However, there are some artificial light sources that can also mimic the natural spectrum and include all the colours visible to the human eye.
- Intensity: Natural light varies in intensity depending on location, time of day, season, and weather. During midday and throughout the day, sunlight is intense, while it is more subdued in the morning and evening. On the other hand, artificial light is typically constant in intensity, but depending on the light source and its settings, adjusting the intensity is also possible.
- Biological Influence: Natural light plays a crucial role in regulating our circadian rhythm due to its varying intensity and spectral properties. It impacts our sleep-wake cycle, mood, hormone production, and even our production of vitamin D. Artificial light can also have a biological influence, especially when it comes to circadian lighting designed to mimic the rhythm of natural light and maintain our biological rhythms.
- Availability and control: Natural light is readily available during the day when the sun is visible. It may not be directly controlled by humans, but we can take advantage of it by positioning ourselves in areas with more or less shading. On the other hand, artificial light is available according to our needs and can be controlled in terms of brightness, colour temperature, and on/off functions to meet our preferences.
Which light source is best for us?
It's difficult to answer, but one thing is certain: Light is a fundamental part of human nature.
If we are not exposed to enough sunlight, it can have several health consequences – both psychological and physical. This is closely related to our circadian rhythm, which is evolutionarily synchronized with the rhythm of the sun. We are designed to be active during the daytime when we need a lot of blue light from the sun to keep our bodies and brains awake. Similarly, we need darkness and as little blue light as possible at night. This ensures that the production of our dark hormone melatonin is preserved. If we are exposed to light without blue tones during the day, we will feel groggy and tired, just as blue light from our TVs and phones can keep us involuntarily awake in the evening, and all of this contributes to disrupting our internal biological clock, our circadian rhythm. In addition, it is only during the day that we have the physical ability to see and navigate the world around us, as the human eye does not have night vision. This also indicates that the night is a time for rest and sleep, because the lack of light makes it impractical for us to be active, while darkness makes it practical for us to rest.
Both natural light and artificial light have their unique advantages and applications. Natural light supports our biological processes and circadian rhythm, as well as supporting many other vital processes on Earth. Artificial light, on the other hand, provides us with flexibility, control, and the ability to create specific lighting environments that suit our activities and needs. So, what is best?
At first glance, one might be led to believe that natural light by definition is the best for us, and in many ways, it is, especially when it comes to its intensity and colour rhythm. However, there are factors such as season and location that make natural light not always sufficient – or even sometimes too much of a good thing. The light from nature is not always enough to keep us healthy and well, and therefore artificial or electric light sources are often an important supplement and even a life-giving necessity for many. The best for humans is therefore to get the right amount of light at the right time.