What Is Blue Light?
Blue light is a perfectly normal and natural spectrum of light that is found in sunlight.
Light ranges from 400 to 700 billionths of a meter (nanometer, nm) 400nm being violet to 700nm being red. When combined the individual spectrums of light create "white light" or sunlight.
Sunlight consists of a range of coloured light including red, orange, yellow, green, blue, indigo and violet - when we see a rainbow we see the light rays from the sun refracted through raindrops and splitting the light spectrums, similar to seeing light through a prism.
The useful range for colour vision in humans is approximately 450 to 650 nm. Visible blue light has a wavelength between 400−525 nm,
High-energy visible light is high-frequency, high-energy light in the violet-blue band of the visible spectrum from 400 to 450 nm. High-energy visible light is found in sunlight as well as in artificial light sources such as fluorescent and light-emitting diode lighting, smartphones, tablets, laptops, televisions, and many other electronic devices.
Is Blue Light Safe?
Blue lights have their benefits and drawbacks, it will depend on how much exposure to blue light you have over how long a time - we are talking years here.
Humans and animals have been exposed to blue light since the dawn of time, we have all felt the positive benefits of the sun on our mood or state of mind, however in more recent years the levels of our exposure to blue light have risen due to the introduction of LED's (Light emitting diodes) and our increasing use of devices such as laptops, mobile phones and e-readers
The Canadian Association of Optometrists (OPTO) states "Evidence suggests that exposure to blue light in the 470 - 490nm wavelength range (lower energy) is less damaging to the eye than blue light in the 400 - 470nm wavelength range (higher energy) and essential for maintaining a healthy circadian rhythm. The development of LEDs with peak emission in the safer range may represent an important advancement for ocular health.
The International Commission on Non-Ionizing Radiation Protection (ICNIRP) provided guideline levels of blue light exposure where they considered health risks to be unlikely.
Range of Digital Device Blue Light Exposure Type of Device
|Type of Device||% of ICNIRP Limit|
|Desktop||0.71 - 1.26|
|Laptop||0.63 - 1.97|
|Tablet||0.43 - 2.38|
|Smartphone||1.78 - 4.09|
Thus, clinicians may conclude that the magnitude of exposure from digital devices does not approach dangerous levels.
When speaking for optician online Dr Shelby Temple senior research associate at Bristol University said "To be exposed to that same amount of dangerous high-energy protons during a 20-minute walk or drive to work, you would need to spend 133 hours looking at your phone or computer screen continuously."
Blue Light And Sleep
Humans and animals alike rely on light from the sun to tell us when to wake up and when to go to sleep, interrupting the natural amount of light the body receives will alter our sleep pattern.
It's not just LEDs that can affect sleep patterns, for many years healthcare professionals have been aware that people exposed to too little light can find their health compromised. Night shift workers can suffer from increased sugar levels, raised blood pressure, heart disease and obesity.
Our natural Circadian rhythm is altered by the amount of artificial light all around us, our circadian rhythm affects our sleep-wake cycle, during daylight our body clock sends signals to the brain to keep us awake and alert, as the light falls at dusk our body clock initiates the production of the hormone melatonin to prepare us for and then keep us asleep.
Interestingly circadian rhythm comes from the Latin "circa diem,” which means “around a day.”
With the increasing introduction of LEDs in lighting and in most modern tech our exposure to blue light does not diminish as the sun goes down so our bodies are not encouraged to produce the desired amounts of melatonin and this can affect our sleeping patterns. This can be great if you need to stay up late studying or partying but not so good if you have that important exam or interview early the following morning.
According to a recently published study, using just an e-reader at night before sleeping while in bed induces circadian phase delay and melatonin suppression, this alters sleep quality and reduces cognitive performance in the morning.
Whilst a late night here or there may make you feel tired and possibly not perform at your best it won't have any lasting effects on your health. However several sleepless nights can seriously affect your health, you can suffer brain fog, lose concentration, and possibly make bad decisions, if sleep deprivation continues you can begin to feel depressed and the risk of accidents whilst driving or at work rises.
The Dangers Of Blue LightOverexposure to blue light has been reported to cause problems not only with our circadian rhythm but with our eye health from the mildly irritating to the more severe.
- Eye strain - is a common issue for those who sit in front of a computer or television for long periods. This problem is known as digital eye strain and can induce headaches, migraines, nausea, tired eyes, increased tear production and blurry vision.
Optometrists and eye professionals recommend taking a 20 second break every 20 minutes by looking 20 feet away to help mitigate digital eye strain
- Snow blindness - also called photokeratitis, is an effective sunburn of the eyes. It’s painful and is usually caused by the glaring of natural light, such as sunlight reflected off of snow or water.
- Ocular cancer - is also linked to overexposure. Just as too much sun exposure to your skin can cause melanoma, too much light exposure can cause ocular cancer. It’s a rare but dangerous form of cancer that is a serious risk, especially for those who live in bright, sunny locales.
- Cataracts - are also a concern. Cataracts cloud the crystalline lens of the eye, dimming vision and eventually requiring surgery. While there are many contributing factors to cataract formation such as age, smoking and genetics, however research into progress about the effect and prevention of blue light on eyes highlighted that blue light can induce the production of ROS in the mitochondria of lens epithelial cells (hLECs), which may lead to the development of cataracts.
- Macular degeneration - Overexposure to blue light is also linked to the acceleration of macular degeneration. some studies have shown that blue light can accelerate AMD occurrence and development after cataract surgery
This disease causes damage to the macula, which are the thin films on the centres of your retinas. As the damage gets worse, sharp central vision fades, leaving only peripheral vision intact.
The Benefits of Blue Light
With all of the dangers above, you may think that living in a soothing, dim cave may be best for you. While low light is a great idea for relaxing and will help you to sleep at night, our bodies require sunlight and the accompanying blue light to produce vitamin D. Vitamin D allows us to absorb and use calcium, which is crucial for strong bones and teeth.
In countries where daylight is short for much of the year, such as Norway, Russia and some parts of Canada, vitamin D deficiency can be a serious issue, leading to health problems. While drinking fortified milk and juice can help, natural exposure to sunlight is the best prevention. According to the NHS most people can make enough vitamin D from being out in the sun daily for short periods with their forearms, hands or lower legs uncovered and without sunscreen from late March or early April to the end of September, especially from 11 am to 3 pm.
We also require light exposure to avoid emotional and psychiatric problems. Seasonal affective disorder (SAD) is characterized by depression that comes with winter and it can be crippling. General depression is also more common in areas that have a lot of grey days, such as the rainy Pacific Northwest in the United States.
How To Protect Yourself From Light DamageThe best way to limit the effects of blue light is to limit your exposure, there are certain steps you can take, including:
- Ditch the tanning bed - Tanning beds expose you to dangerous levels of light. Even if you wear goggles to protect your eyes, your skin will pay the price. If you just can’t bring yourself to accept your porcelain glow, make the switch to self-tanner or spray tan.
- Cover up. If you spend long amounts of time outdoors, wear sleeves, long pants, sunglasses and a wide-brimmed hat that keeps the sun off your face, neck and ears. The wide-brim hat will also help shade your eyes, protecting you from glare and reducing the amount of light that enters your eyes.
- Change your schedule. Avoid making appointments that require you to drive into the sun, if possible. If you’re going to the beach or pool, avoid the hours between ten and three when the sun is at its worst. If you jog or hike, take advantage of the early morning and evenings for more privacy on the trails and less exposure. If you want to enjoy the park on a sunny day, plan to arrive later in the afternoon to take advantage of the sunset and the cool, quiet twilight.
- Limit excessive screen time. Make a schedule and stick to it. If you have a habit of sitting in front of your computer and mindlessly surfing, limit your time. If you want to enjoy the park on a sunny day, plan to arrive later in the afternoon to take advantage of the sunset and the cool, quiet twilight.
How To Protect Your Eyes From Blue Light Damage
Some of the steps you can take to protect your eyes are:
- Wear sunglasses or coated lenses. If you know you are going to be exposed to excessive blue light, wearing UV-blocking lenses can limit the amount entering your eyes and potentially cause damage. You won’t need sunglasses for the five-minute stroll to the corner store and back, but you will want protective lenses if you’re going to spend a day on the slopes or an entire night working on the computer.
- Take frequent breaks. Taking a break from the light exposure and allowing your eyes to rest and refocus can help avoid eye strain. Take a break every half hour while working at the computer. Look out a window and focus on a point in the distance and you’ll be able to feel your eyes relax.
- Install a blue light filter app on your devices. If you’re constantly on your phone or tablet, a blue light filter could help avoid eye strain. Of course, this is just a stopgap measure. You will still need to limit your time on devices and hold it away from your face to avoid eye strain.
- Get blue light blocking glasses. Computer glasses by Gunnar are available on Amazon for around £40 - £60 which block blue light. Gunnar glasses provide a small magnification as well. People with presbyopia can get prescription computer glasses as well.
Before heading out to your local optical retailer it's worth bearing in mind that some unscrupulous retailers are trying to increase sales on the back of public fear
Blue light has made headlines in the UK and around the world due to concerns that it could damage vision. Optical retailers Boots and Vision Express were busted by BBC One’s Watchdog program. Investigators posing as shoppers caught salespeople overstating the dangers and using alarmist talk to con consumers into high-end lenses purported to protect your eyes from blue light. These undercover operations captured six health claims being made, none of which are backed up by evidence. Some claimed that blue light emitted from electronic devices can damage the eyes, while others said their lenses could prevent that damage. Like many sales tactics, this one piggybacks off of real science and frightens people who don’t have the specialized knowledge to separate fact from fiction. The inclusion of half-truths makes it easier to fool a well-educated person whose specialty isn’t optometry or ophthalmology. Understanding the truth about blue light will give you the necessary tools to protect your vision and your pocketbook.
More studies are needed on the long term effect of blue light particularly on children and teenagers who will potentially be exposed for prolonged periods of time over many years. Whilst various studies have proven that blue light does have the potential to cause harm to your vision if you are overexposed, screen time is not harmful enough in itself to pose much of a problem, however it can interfere with your natural sleep pattern. Limiting your exposure and taking appropriate precautions when you are exposed are the best steps you can take to avoid blue light damage to your eyes.
Author: John Dreyer Optometrist Bsc(Hons), MCOPTOM, DipCLP
Created: 26 Jun 2017, Last modified: 3 Jan 2023