Blue light: Frequently asked questions

What is blue light?

Blue light is part of the light spectrum. It occurs in our natural environment because it is present in the greatest quantity in the light that comes from the sun.  Blue light is required for healthy development and sleep regulation and in fact keeps us awake.  Blue light is not ultra violet (UV) light which is known to cause damage to the eye and which is why people are urged to wear UV sunglasses.  Experts say that the blue light which comes from digital devices is not harmful and is a fraction of the blue light that comes from the sun.

Says ophthalmologist Dr. Sunir Garg : “the amount of radiation or blue light spectrum light that comes to our eyes from a screen is much less than we get from being out in the sun on a normal sunny day in the summer.”

Is blue light from digital screens harmful?

The American Academy of Ophthalmology says there is no evidence the light coming from our digital screens is damaging to the eyes,
Many experts including optometrists,  ophthalmologists, and an optical radiation expert all tell Marketplace there is no scientific evidence that “harmful blue light” is emitted from digital devices like smartphones, tablets, and computer monitors.
In fact, they say, while there is blue light emitted from these devices, there is no scientific evidence that it is harmful.

Does blue light from our screens affect melatonin and sleep?

Yes, blue light keeps us awake. And since most blue light in our lives comes from the sun, it wakes us up in the morning and keeps us awake throughout the day. Spending time on our screens in the evening is not a good idea because our bodies should be getting ready to sleep and even a small amount of blue light can affect our melatonin levels and disrupt the natural awake-sleep patterns.
There is evidence that blue light from digital screens can affect the body’s circadian rhythms, so the American Academy of Ophthalmology does recommend “putting down your phone or computer” a few hours before bedtime, and/or switching to night mode on all devices.

Why do my eyes feel sore and tired after being on my smartphone or laptop all day? Isn’t that from blue light?

People blink far less during computer use and blue light filters have not shown any improved “visual comfort” for digital eye strain, according to experts.

Experts say if the problem people are having is from digital eye-strain, then blue light filters are doing nothing to address the core issue and “could be doing more harm than good.”

How do I fix digital eye-strain, and make my eyes stop hurting when I’m on my screens?

A simple fix for digital eye-strain is called  “the 20-20-20 rule.”  Look at least 20 feet (six metres) away from your screen for 20 seconds every 20 minutes.

Can’t blue light filtering lenses help with things like eye fatigue?

A 2017 study found no evidence that blue light filtering glasses offered any significant protection against eye fatigue, sleep quality, or macular damage.

Is blue light from your screens at a level that is harmful?

Research from Public Health England found that blue light from digital screens is at a level that is not at all harmful - even if it is stared at all day.

Can blue light from digital screens cause macular degeneration or glaucoma?

The UK Association of Optometrists’ Position Paper states “there is currently no evidence to suggest that visible blue light has any effect on the development of eye conditions such as age-related macular degeneration (AMD) or glaucoma.”

The Macular Degenerative Foundation tells us “there isn't much evidence to support wearing blue light blocking lenses for everyday electronics use. Little evidence currently exists to suggest either that this level of blue light exposure is damaging to the eye or that the current glasses on the market offer any significant protection.”

Does blue light from digital devices makes you feel tired or fatigued?

No - Experts say blue light actually makes us more alert.

Can blue light filters reduce eye-strain?

Experts have told us there is no scientific evidence that blue light from digital screens causes headaches or eye-strain, or that blue light filters will reduce the symptoms of digital eye-strain (DES). 

What about the studies around blue light?

We asked an expert - Dr. Sunir Garg -  to review the studies some companies sent to us in order to determine if any showed that blue light specifically from digital screens is harmful.

One 2018 study from the University of Toledo is commonly cited, however the American Academy of Ophthalmology (AAO) offered notes of caution about this study
The experiments do not mimic what happens in live eyes.
The cells that were tested are not derived from retina cells.
Cells in the study were not exposed to light in the way cells in the eye are naturally exposed to light.
The part of the cells that was affected by retinal in the experiments (the cell membrane) does not touch retinal in the eyes of living people.

Here were Dr. Garg’s responses to some other studies:

a) Removal of the blue component of light significantly decreases retinal damage after high intensity exposure https://eprints.ucm.es/47172/1/Celia%20Sanchez%20Ramos_%20PlosOe-2018-journal.pone.0194218.pdf
Dr. Garg told us this study was “not relevant” as “the mice were albino mice (which can't recover after light injury well) that were dilated (our pupils constrict to bright light) and exposed to 5000 Lux (your kitchen is 100). “

b) Research progress about the effect and prevention of blue light on eyes http://www.ijo.cn/en_publish/2018/12/20181220.pdf
Our expert told us “this is  a review paper and hard to draw any meaningful conclusions”

c) Blue light induced retinal oxidative stress: Implications for macular degeneration


He told us this is “mostly studies of cells, not of the eye as it exists in people”.

d) Evidence for the Role of Blue Light in the Development of Uveal Melanoma (UM)
Dr. Garg told us this might be “hypothesis generating” but there is “no data”.

e) Influence of blue light on photoreceptors in a live retinal explant system
Dr Garg says, “as in petri dish no filtering of blue light from anterior segment” and also “1mW/cm2 is really really bright and not representative of me sitting in front of my screen”.