Blue light-Blocking Glasses
How many of you have spent money on clear lense blue light glasses
or a blue light filter on your actual glasses? (I definitely have in the past .. ugh!)
I want to break down a few points and the science behind everything,
as well as how this all ties into you and your baby’s sleep!
#1 - Light directly affects melatonin production in our brain.
Blue/green light with shorter wavelengths suppress melatonin while
red/orange light with longer wavelengths promote melatonin levels.
Research has shown us that blue light with wavelengths between
470-525nm suppresses melatonin production (1).
Less melatonin = more alert and less sleepy.
#2 - Clear lenses can only block up to 40% of actual blue light.
If we want a lense to block more and more blue light, then the lense colour
starts to change colour to yellow, then orange, then red.
With a clear lense there is no regulation for blue-blocking percentage,
so you could be getting 3% blue blocking on your glasses or you could be getting the full 40%...
and good luck trying to find out what the percentage is on the company’s website!
Check out this quote from eyekeeper.com regarding a specific pair of their blue blocking glasses
– “They block 93% to 99% of light within the 400- to 420-nanometer wavelength range,
and they block around 24% of 500-nanometer wavelengths.”
Only 24% of 500nm wavelengths !?
Remember the blue light that effects our circadian rhythms ranges from 470-525…
so for them to block the higher spectrums (violet/purple light) doesn’t do anything
for our circadian rhythms because those wavelengths are weaker (2).
#3 - 40% Blocking is still something though…
You are right, 40% is something, however it’s extremely hard to find out what
percentage your clear lenses are blocking + during the day… you still need some blue light!
Blue light is needed to keep melatonin production suppressed so we can be active and alert throughout the early parts of the day!
So even if those clear lenses did block the full 40% and they did have an effect on your circadian cycle…
if you're wearing those all day they would be impeding your normal circadian rhythm.
What we want to look at is your motivation behind wanting these glasses.
Do you want them for eye strain?
Do you want them to help you sleep?
#4 - “But aren’t they supposed to help with digital eye strain?”
No. The answer is no. There is no good evidence to suggest that blue blockers -
clear or coloured lenses - help with eye strain.
There is evidence however to show that staring at screens for long periods of time,
and having a screen close to the eyes both strain the eyes.
(4-6)
#5 - If you want them to help you sleep and get your circadian rhythms on track,
then take a look at your routine first. You want to get some good bright light in the morning
and then into the afternoon and evening you want to block that blue light.
You can put an automatic filter on your screens so when the sun begins to go down,
the screen turns amber. (If you have a Mac this is called “Night Shift”)
Another way to block that blue light is by wearing some yellow to red coloured lenses.
Yellow block approximately 60-75% of the blue light and orange lenses block 99% of blue light.
Red lenses are great for *just before bed.*
They block purple blue and green light, so they shouldn’t be worn during the day at all,
just in the hours leading up to bedtime (1).
#6 - So how does this tie into my child’s sleep? Teenie tiny blue-blocking glasses at night?
Not quite, but understanding how light effects our brain is so important and
helps make your child’s sleep environment as ideal as possible!
Keeping an eye on the types of lights in their room, or the lights they are exposed
to before bedtime, and making sure they get lots of bright light in the morning is awesome.
Putting a lot of emphasis on the light vs dark cycle will help train your child’s developing circadian rhythms.
So I don’t have any specific recommendations for types of tinted blue-blocking glasses
because there are so many out there. My only suggestion is you dig deep into the
details and specs of the glasses you buy because they could be “orange glasses” but they are
lightly tinted and won’t block the percentage of blue light you hope it will.
Contact me if you have any questions, I’d love to chat more about this with you!
Hope you have an awesome weekend,
-Marina
Wright HR, Lack LC. Effect of light wavelength on suppression and phase delay of the melatonin rhythm. Chronobiol Int. 2001 Sep;18(5):801-8. doi: 10.1081/cbi-100107515. PMID: 11763987.
Bonmati-Carrion, M.A., Baño-Otalora, B., Madrid, J.A. et al. Light color importance for circadian entrainment in a diurnal (Octodon degus) and a nocturnal (Rattus norvegicus) rodent. Sci Rep 7, 8846 (2017). https://doi.org/10.1038/s41598-017-08691-7
Ari Shechter, Kristal A Quispe, Jennifer S Mizhquiri Barbecho, Cody Slater, Louise Falzon, Interventions to reduce short-wavelength (“blue”) light exposure at night and their effects on sleep: A systematic review and meta-analysis, SLEEP Advances, Volume 1, Issue 1, 2020, zpaa002, https://doi.org/10.1093/sleepadvances/zpaa002
Singh, S., Downie, L. E., & Anderson, A. J. (2021). Do Blue-blocking Lenses Reduce Eye Strain From Extended Screen Time? A Double-Masked Randomized Controlled Trial. American Journal of Ophthalmology, 226, 243–251. https://doi-org.ezproxy.tru.ca/10.1016/j.ajo.2021.02.010
Palavets, T., & Rosenfield, M. (2019). Blue-blocking Filters and Digital Eyestrain. OPTOMETRY AND VISION SCIENCE, 96(1), 48–54. https://doi-org.ezproxy.tru.ca/10.1097/OPX.0000000000001318
6. Rosenfield, M., Li, R. T., & Kirsch, N. T. (2020). A double-blind test of blue-blocking filters on symptoms of digital eye strain. Work, 65(2), 343–348. https://doi-org.ezproxy.tru.ca/10.3233/WOR-203086
