Effects of Blue Light

What is Blue Light?

To understand the effects it is first important to understand what blue light is and where it comes from.

Full Spectrum (red to blue light) of Light On a Bridge

The two extremes of the visible spectrum of light are red and blue light, the former having long wavelengths, 620-750nm, and low energy. Blue light has much shorter wavelengths in the 400-550nm range. The shorter the wavelength, the higher the energy. These high energy blue wavelengths collide with air molecules, scattering more efficiently through the Earth’s atmosphere. In addition to increased scattering, blue light penetrates deeper into the eye due to these properties.

Blue light is all around us, with the main source being from sunlight. However, as the presence of artificial lighting and display lit screens is ever increasing, so is our exposure to blue light.

What are the effects?

Blue light is an essential part of the visible spectrum, without it the sky and sea would appear completely different! The body also uses blue light from the sun to regulate your circadian rhythm (natural sleep/wake cycle, brain activity, cell regeneration), increase alertness and elevate mood. So why the concern?

LED emission spectra are significantly different to natural sunlight, and have relatively higher emissions in the 400-550nm range. The proximity and time spent under this lighting is the issue. The exposure to blue light, especially late at night can alter the natural circadian rhythm of the body. As mentioned above there is increased scattering, causing flickering and glare, which after long periods of time looking at computer screens or other LED devices may be a cause of headaches, physical and mental fatigue. In addition, as blue light penetrates deeper into the eye, prolonged exposure may cause retinal damage and increase the risk of macular degeneration.

Blue light from mobile phone at night

It is not just humans that are influence by blue light, it can effect the melatonin regulation and circadian rhythms of other mammals. It has an even greater impact on insects who tend to have eyes that are more sensitive to UV and low wavelength lights. Research has also shown such light to have increased negative effects on astronomy and sky glow.

What can you do?

There are many apps available that filter out blue light such as f.lux and Apple’s Night Shift mode, which can help if you need to look at an electronic device at night, however, they do not provide a complete solution. A recent study by the Lighting Research Center tested out the effectiveness of such apps, and found there to be a partial decrease in melatonin suppression by changing screen colour, and for a greater effect brightness should also be lowered. Recommendations from the Lighting Research Center include keeping light levels low, limiting use of PEDs (portable electronic devices) to one-hour sessions, and avoiding exposure to PEDs two hours before bed. With the presence of LEDs, technology and PEDs ever growing, this may prove difficult to do!

What are we doing?

LED manufacturers are starting to produce lights with different spectra, and we are developing equipment to help measure and verify their performance in the field, so that the exposure of blue light can be monitored and controlled.

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