The human eye is sensitive to visible light in the section of the spectrum where colours are seen such as from violet, indigo, blue, green, yellow, orange and red light. Blue Light has a very short wavelength, and so produces a higher amount of energy—enough to naturally penetrate all the way to the back of the eye, through the eyes’ natural filters.
Sunlight is the primary source of Blue Light, though in reality, most people get very limited exposure to sunlight these days. The section of the spectrum is actually very important and necessary for our body as Blue Light makes up the Sleep/Wake/Memory cycles.
But there are also the damaging effects of Blue Light from digital devices. The time people now spend staring at phones or tablets can have a harmful effect on sleep patterns and a possible long-term impact on eye health.
Most people cannot last a day without using some form of digital device. We have more digital tools at our disposal than ever before, and even new smart TVs and low energy LED lighting also all emit Blue Light, adding to the compounding effects of exposure.
According to one American study, children and teenagers aged 8-18 were found to spend more than seven hours a day consuming electronic media, whilst 65% of adults spent more than five hours a day using a device.
To protect the eye, macular carotenoids such as Lutein and Zeaxanthin play a role in the protection of the retina against light-induced damage by increasing macular pigment density.
Epidemiological studies provide pivotal evidence that increasing lutein and zeaxanthin in the diet demonstrates a lower risk for age-related macular degeneration by deposition of the carotenoids into these tissues.
Protecting ocular tissue against photo-oxidative damage from Blue Light by these carotenoids acts in two ways: first as filters blocking the damaging Blue Light, and second as antioxidants specific to the eye. The macula and retina in the eye contains about three times higher concentrations of lutein and zeaxanthin than the average levels in other tissues.
Lutein is naturally present in mother’s milk, indicating a protective action of the eye in infants. This is particularly important as infants cannot down-regulate blood flow to the retina as well as adults. Therefore, blood vessels deliver excess oxygen to the retina which favours the generation of damaging free radicals.
As well as improving macular pigment density, and reducing effects of Blue Light exposure, lutein also reduces glare recovery from light and supports contrast sensitivity in the eye which helps with eyestrain.
Now special glare-reducing anti-reflective coatings used in eyewear can help block Blue Light from both natural sunlight and digital devices. Apps and functions on smartphones can be applied to devices to reduce the amount of Blue Light emitted by a screen. Numerous complementary medicine brands also have supplements which can be taken to help lutein andzeaxanthin intakes.
Over the last 20 years a great deal of scientific research has been conducted on the effects of visible light on the suppression of melatonin production. Melatonin is the hormone secreted by the pineal gland in the brain which maintains the body's circadian rhythm. This is the internal 24-hour 'body clock' that plays a critical role in when we fall asleep and when we wake up.
Research is showing that there is differential sensitivity of the circadian system to different light wavelengths, and that melatonin suppression is more sensitive to shorter high-energy wavelength light (such as Blue Light) than longer wavelengths which have less energy.
Studies conducted on various wavelengths of light, including red, amber, green and blue, examining their ability to suppress melatonin production showed that the shorter wavelengths of Blue Light has the greatest melatonin suppression by up to 81%.
Other studies showed that, when compared with dim light, exposure to standard room light during the night suppressed melatonin by almost 85%. Therefore people may have difficulty getting to sleep and staying asleep due to ‘light exposure’ from night lamps. Insomnia in adults has been linked to an increase in depression, diabetes and cardiovascular conditions.
These results are hardly surprising as Blue Light wavelengths conversely boost attention, reaction times, and mood — thus are required during daylight hours when we are more active and when sunlight is available.
Interestingly, researchers at Harvard University have also been investigating the effects of Blue Light in comparison to Green Light. The study found that Blue Light suppressed melatonin for almost twice as long as the Green Light and affected the circadian rhythms for double the time period.
Other studies have found that blue wavelengths of light also suppress delta brainwaves, which induce sleep, and boost alpha wavelengths, which induces alertness.
In order to reduce the problematic effects on sleep we need to avoid any exposure to Blue Light for up to 60 minutes prior to bed. To do this people need to turn off their TV, tablets, computers and smartphones. The surrounding environment also needs to be dimly lit so that the body is encouraged to naturally start producing the melatonin it needs to fall asleep.
- Gulhan Demirci has been the technical and regulatory manager at Caruso’s Natural Health for over 10 years. She has developed over 200 supplements, creams and food products for the company.