We’re all familiar with the colour blue, but what exactly is blue light and what does blue light exposure mean for us?

To answer that, we first need to understand that light itself is a form of energy. The colour of any light is determined by its wavelength, which is measured in nanometres (nm) - a unit so small that one nanometre is a millionth of a millimetre. When we talk about light, we’re referring to the range of wavelengths that our eyes can perceive, known as the visible light spectrum. The visible spectrum includes a collection of different wavelengths, each corresponding to a different colour.

Blue light falls within the shorter wavelength range, typically between 400 and 500 nm, and appears at the cooler end of the visible spectrum. When we break down this spectrum, it’s traditionally divided into six broad colour bands: red, orange, yellow, green, blue, and violet. Blue light occupies the part of the spectrum just before ultraviolet light, which is invisible to the human eye. Because blue light has a shorter wavelength, it carries more energy than other visible light colours such as red light or yellow light.

The source of blue light and its effects on our health

Blue light is emitted naturally by the sun, playing an essential role in regulating our circadian rhythm and keeping us alert during the day. This natural source of blue light is part of daylight, and our exposure to it during the daytime helps us stay awake and focused. However, blue light exposure doesn’t just come from the sun anymore. We are now surrounded by artificial sources of blue light from digital devices like smartphones, tablets, computers, and LED light bulbs.

While blue light from the sun is beneficial during the day, prolonged exposure to blue light from digital devices can have unintended effects on your health, particularly your eyes and sleep. This constant exposure can interfere with your sleep cycle by suppressing melatonin, the hormone that helps you sleep.

How blue light affects your eyes and health

Prolonged blue light exposure from digital devices can cause digital eye strain, leading to discomfort, dry eyes, headaches, and difficulty focusing. The potential long-term effects of blue light are still being studied, but there is concern that too much exposure might contribute to retinal damage over time.

To help protect your eyes, there are solutions like blue light glasses, which are designed to block or filter out harmful blue light, and computer glasses with yellow-tinted lenses that reduce strain. Some screens and devices also emit less blue light in specific modes, such as “night mode” or “blue light filter,” which shift the screen's colours to warmer tones, making it easier on your eyes.

Reducing exposure to blue light from digital devices

Given the widespread use of screens and the constant blue light exposure they produce, it’s important to find ways to manage it. Reducing screen time in the evening, using blue light glasses, and enabling the blue light filter on your devices are all steps you can take to limit your exposure. Additionally, choosing lighting solutions that emit less blue light, such as warmer-toned LED bulbs, can help reduce its impact on your eyes and sleep.

Conclusion: protecting your eyes from blue light

In essence, blue light is a significant part of the visible light spectrum, with wavelengths ranging from 400 to 500 nm. Its evolution from a natural source to a constant presence in our digital lives means it's more important than ever to manage our exposure to it. While blue light plays a crucial role during daylight hours, too much exposure to artificial sources can negatively affect both your eyes and sleep cycle. Protecting your eyes from the potential health effects of blue light is essential, especially with the amount of time we now spend in front of digital devices.