Is blue light dangerous?

The latest Colourchat video discusses whether blue light is dangerous. In this video we discuss the effect of light on our skin, our eyes and our sleep.

0:00 Introduction
3:41 The effect of light on skin
7:28 The effect of light on our eyes
9:39 The effect of light on sleep
14:49 Ending

Link to Prof Blackburn’s work on the efficacy of sun-protection products
https://www.leeds.ac.uk/news-health/news/article/4937/reduced-protection-of-some-sunscreens

Hi I’m recording today from the lighting Lab at University of Le we have this very uh special lab where we can change the color of the lighting in the room um it’s not just changing it with red green and blue lights it’s literally changing it spectrally so we can Define the

Spectral uh distribution of light in the room and um you’ll see it changing during the course of this video uh cycling through various various colors and I thought this was very appropriate today because uh I’m going to talk about light today and in particular I’m going

To talk about the question is blue light uh dangerous and of course we take for granted that when we say dangerous we mean dangerous for humans not for for example uh prawns or some other thing um but what do we mean by Blue Light well blue light is normally

Considered to be about 450 to 48 80 nanm below that we have violet light and the lowest wavelength that’s visible to us is usually about 360 nanometers it actually depends on intensity it varies from person to person but but let’s say 360 NM because the cie uh defines light as those

Wavelengths from 360 to 780 nanometers and then below that we have UV light in the range 100 to 400 nanom so actually there’s an overlap between UV light and visible light light at say 380 NM is both UV light and is also in the visible range so when people ask whether blue

Light is dangerous they’re they’re normally referring to just short wavelength visible light perhaps some some UV light as well um rather than strictly speaking the light in a very narrow range 450 to 480 NM so in this video I’m I’m going to look at Short wavelength light and also

UV light and look at whether any of these things are dangerous so first of all we can say is radiation at any of these wavelengths dangerous to us and the the answer of course is that yes and no and or it depends it’s yes because exposure to light at

Any wavelength even in the visible spectrum will kill you if the intensity is high enough and it’s no because a single Photon of light at any wavelength in the visible spectrum will cause no harm whatsoever so we always have to bear in mind that whether it’s dangerous depends upon the

Intensity and the exposure time we might call that the dose but if you Google whether blue light is dangerous you’ll get lots of images like this and like this why is this well there are two things I’m going to talk about in this video um the first

Is going to be potential damage of short wave length light to the skin and to eyes and the second thing is going to to be potential damage of short with light to our um healthy sleep patterns so um the first of these is based on the fact that the shorter wavelengths of

Light are more energetic and by that I mean that the photons or packets of Light have more energy the shorter the wavelength so UV light is more energetic than light IND the visible spectrum and UV light is normally split into three bands the um the most dangerous is um

UVC um this is 100 nanometers to 280 nanm very short wavelength uh very dangerous UVB is 280 to 350 nanm an UVA is the least dangerous it’s 315 to 400 nanometers that’s the one that overlaps a little bit with the visible spectrum now natural sunlight the light

Coming to the earth from the sun obviously contains visible light but it also contains UVA UVB and UVC but the good news is those very very short wavelengths UVC tends to be absorbed by the Earth’s atmosphere so we don’t need to worry about that in terms of natural

Light but what about UVA and UVB well they can both penetrate our skin UVA penetrates deeper UVB only penetrates the top layer of the skin which is called the epidermis but it can still do a lot of damage there and in fact both UVA and UVB can cause damage to the

Skin we do need some exposure to short wavelength light lighting generally is is healthy um it helps the body to produce vitamin D for example and early in the 20th century it was discovered that exposure to light and and also consumption of cod liver oil um could

Prevent or cure a disease uh called rickets um which incidentally I I I actually noticed in the news yesterday is is um is start to become um slightly more common again in in the UK which is quite concerning which is to do with diet I think primarily what’s interesting um is that

UVA and UVB can both literally damage the DNA of your skin and this can lead to cancer skin cancer if you get sunburn then this is a clear sign that you’ve been exposed too much um and you’ve got skin damage sunburn is definitely not a good thing thing skin cancer is actually

The most common cancer in the USA it’s estimated that one in five Americans will develop skin cancer at some point in their lives nearly 10,000 people are diagnosed with skin cancer in the USA every day it was literally announced today that Sarah Ferguson ex-wife of prince

Andrew in the UK has been diagnosed with skin cancer in her case um malignant melanon Mel melanoma which is the worst type how serious this is for her depends on how early it’s being detected so blue light and near UV light is dangerous to our skin if the

Intensity is too high and the exposure too long the other way um light might be dangerous in this sense is to our eyes so UVB is absorbed by the corer the outer part of the eye and also by the lens um so we really have to worry about

UVA but there’s some argument that UVA can literally destroy the light sensitive cells the cones that enable us to see some research suggested that exposure to too much light um is a risk factor for something called age related macular degeneration this is a type of blindness it’s a condition developed in

Many old people where the central part of the retina is damaged so that you can’t see things if you look directly at them makes it very difficult to read for example it’s like having a huge uh blind spot right in the center of your vision so the potential danger here is

Literally being outside working or on holiday in really bright conditions people might think of sunglasses as being a fashion ACC accessory but I would argue they may be really important to protect your eyes if you’re out uh for long periods and it’s very bright and sunny uh some people think that looking

At your computer screen can cause this damage to your eyes since your computers and phone displays emit uh blue light though not UV light you can even buy so-called nerd glasses to protect you when using your computer these are yellow lenses or filters that can um

Remove the UV load or sorry remove the remove the blue load however it’s extremely unlikely that you could get this sort of retinal damage using a computer screen or a phone screen for example the light outside on a bright day is Thousands if not tens of thousands of times uh brighter than the

Light emitted by your computer so far I’ve C covered the potential danger of UV and blue light Outdoors to our skin and eyes the second thing I want to talk about um is whether blue light is dangerous in terms of the effect on our sleep we have an approximately 24-hour

Pattern of sleeping and waking but what is the purpose of sleep this is the very question that has preoccupied Matthew Walker for the last 20 years or so and I can’t recommend highly enough his book why we sleep it turns out that not getting enough sleep actually not getting the right amount of

Sleep because too much can also be a bad thing has an adverse effect on almost every aspect of our health increased risk of heart disease cancer obesity diabetes Etc not to mention mental health around a quarter of a century ago it was discovered that in addition to

The three types of cones and the rods in the retina of the eye that give us Vision we have a fifth photo receptor this is based on a pigment called melanopsin and it’s particularly activated by blue light and the interesting thing about these photo receptors is that whereas cones and rods

Send their signals to the back of the brain uh the visual cortex in the the acial lobe of the brain where Vision takes place I would argue these special feder receptors send signals mainly to a more Central brain region which controls a number of non visual functions such as body

Temperature and the release of various hormones so we have this 24-hour sleep cycle and our body releases a hormone called uh melatonin as we fall asleep and then in the morning it stops doing that and it starts to produce hormones like cortisol and and serotonin and uh this

Helps you wake up and get energized for the day and if you’re like me getting a bit older you also need to have a good coffee to help the process along so we now know that exposure to light helps to entrain the timely release of these hormones one study for example found

That looking at your smartphone displayed just before you sleep inhibited the release of melatonin and this can upset your natural healthy sleep patterns with some negative health risks you might not even notice it but you might sleep a reasonable length of time but not get the the quality of sleep

Needed there’s a type of sleep called um deep sleep or RM sleep which is thought to be particularly important we’ve evolved to be exposed to lots of light in the morning and not much at night in the past when we worked in the fields um and agriculture was our main

Activity we would naturally get lots of exposure to light in the morning and then in the evening we might only have fire light or candle light not only are these lights not very bright but they contain very very little short wavelength light the type that particularly activates these special photo

Receptors so many researchers today are concerned because first of all we might be getting too much exposure to short wav Dent light in the hours before sleeping and secondly we might not be getting enough light in the morning of course some of you will have heard of Seasonal effective disorder

It’s a type of winter based depression that is is often treated with a bright light in the morning one study found that use of light therapy like this was about as effective as anti-depressants one of my uh PhD students here at Le University mongan um is using this this lighting lab I’m in

Now to try to establish whether exposure to light in the morning would be beneficial in health terms particularly Mental Health to everyone not just people diagnosed with Seasonal effective disorder I also worry about care homes for the elderly and whether residents get enough access to light in the

Morning especially in places such as the UK and Northern Europe where during the winter there’s not much Morning Light ideally we’d like these Care Homes to be fitted with what we call Dynamic lighting where the lighting is very bluish and intense during the morning but then gradually gets less intense and

And warmer as the day progresses it’s not expensive to do this these days with um lowcost um lighting technology and and computing power um but I think there’s a lack of awareness about this problem so let’s summarize what I’ve been saying because there are a couple of things firstly short W life

And UV light is potentially dangerous to us in some cultures having a tanned body may be attractive but you need to ask yourself whether the risk of skin cancer is worth it suntanning booths and shops are banned completely in Australia and personally I think they should be banned

Everywhere there’s no such thing as a safe tan and Sun creams may not even provide the protection that they claim and in the description below I’ll put a link to an article by my colleague Professor Richard Blackburn who is an expert about this this very topic so secondly there is potential

That too much exposure to Bright Light may increase risk factor of a type of blindness called macular degeneration but it’s not proven there is a concern but to be honest there are other risk factors that may be more important the most important risk risk factor for Market degeneration is is literally age

The older you get the more likely you are to um contract it and I don’t certainly don’t think anyone needs to worry about using their computers in ter ter of risks to damage to the eye however the third area I spoke about was the effect of light on sleep and

This is a a very serious concern um it’s probably a good idea not to use your phone or tablet in bed just before you sleep um now if you do consider using night mode or or just turning the brightness down and that would probably be okay and remember that getting enough

Light in the morning may be just as important as avoiding too much in the late evening and if you do want tips about how to get better sleep I really do recommend Walkers book it’s not just about light he talks also about other considerations to to get better sleep including um room

Temperature so if you if you like this do do please like the video because uh if for no other reason then it makes me feel um a little bit happier uh seeing seeing that um and with that see you next time