How does Blue Light affect sleep?
Blog reposted from BluBlox.
Full disclosure, Float Seattle is an affiliate of BluBlox. Whether or not you choose to purchase any of their products, we stand by the info in this article and strongly encourage bluelight blocking glasses for screen time at night at the very least. They’ve been a game-changer for my sleep! BluBlox glasses are great quality, too - Andrew
You have probably been hearing a lot about blue light recently, and how it can cause health issues and disrupt your sleep. Chances are you are struggling to find credible information on how blue light affects sleep. You are a critical thinker and you do not want to take someone’s word that blue light affects your sleep.
Rightly so!
In this article we are going to explain to you how blue light affects your sleep and link some of the important peer reviewed studies and clinical trials on this very question; how does blue light affect sleep?
Blue Light and Melatonin… Oh, and Green Light too!
Melatonin is a powerful hormone that is produced in our bodies a few hours before and during sleep. Melatonin helps us get into the correct sleep cycles and improves our sleep quality and quantity. Melatonin is also a powerful antioxidant that allows apoptosis and autophagy to occur whilst we sleep which keeps our cells healthy and disease free. Melatonin has also been shown to improve our immune systems, our longevity and our overall health and wellness. This sleep hormone is essential for an optimal and healthy life.
Melatonin can only be released in the absence of blue and green light between 400nm and 550nm. In 2001 a very important study was released called “Action Spectrum for Melatonin Regulation in Humans”.
This study showed that melatonin suppression increased in a bell curve like fashion between the wavelengths of 400nm to 550nm. To you and I this is all blue light and most green light. This type of blue and green light is found in all back lit digital devices like smart phones, tablets and laptops and in TVs, house lights and even your fridge light. This blue light and green light is what turns off your melatonin production and prevents you from sleeping well. Blue light affects sleep by turning off melatonin production which then causes us to feel more awake when we should be feeling tired, preventing good quality restorative sleep.
Again, in 2001, Wright and Lack released a paper analysing different light wavelengths and their effect on melatonin production, when exposed after dark.
They compared 660 nm (red), 595 nm (amber), 525 nm (green), 497 nm (blue/green), and 470 nm (blue) wavelengths.
The shorter wavelengths, 470, 497 and 525nm showed the greatest melatonin suppression, 65% to 81%. The shorter wavelengths also showed the greatest circadian phase delay ranging from 27-36 minutes (in essence exposure of these frequencies of light delayed the participants falling asleep).
In 1991 a study emerged in Sleep by Horne et al. which showed that green light from 500-530nm suppresses melatonin.
In 2010, Gooley showed that mid-green light has a similar effect on suppressing melatonin as that of blue light. However during the light exposure the spectral sensitivity to the green light decayed exponentially relative to the 460nm blue light. Showing that we should not disregard blue light when looking at blocking artificial light after dark for optimal melatonin secretion.
Circadian Rhythms
In order to understand how blue light affects sleep it is important to understand how blue light influenced the evolution of our circadian rhythms. Almost every creature on earth has a circadian rhythm which is another term for our body clock. These rhythms evolved under the sun and darkness. Our circadian rhythms are what manages our hormone production and keeps us healthy.
Circadian Rhythms are governed and entrained by natural light and dark cycles. Blue light from the sun during the day (very much in layman’s terms here) tells our body clock that its daytime and to keep cortisol levels high which is great for feeling active. When this blue light disappeared after the sun had set it sent another message to our body clock to advise it that its now night time and to stop producing cortisol and to start producing melatonin.
In our modern world, we no longer live under ancestral light and dark cycles which is what our circadian rhythms have evolved under. We work indoors during the day under too much blue light and then after work we go home and subject your circadian rhythms to mini artificial suns in the form of our smart phones, laptops, TVs and house lights. These devices all give out blue light which tricks our brains into thinking its daytime and to not shut down cortisol levels and suppresses melatonin. By having blue light in our homes after sunset we are in essence living in constant daytime, which our circadian rhythms cannot handle and subsequently affects our sleep in a negative way.
How to Improve Your Sleep By Managing Your Blue Light Exposure
It is very clear that blue light and green light are impacting and affecting your sleep in a negative way. Harvard Health and multiple peer reviewed studies have shown this without any compromise.
But how can you stop blue light negatively impacting your sleep and health?
These five tips will help you manage blue light exposure and sleep better.
Wear Blue Light Glasses
Blue light glasses can help stop blue light from affecting your sleep. The best blue light glasses are ones which stop 100% of blue and green light between 400nm and 550nm hitting your eyes. This, according to Brainard et al in 2001 is the exact range of light to block post sunset in order to positively affect sleep cycles. These glasses filter out damaging blue light and green light and enable optimal melatonin production and optimal sleep. The best blue light glasses are Sleep+ and have been positively affecting the sleep of tens of thousands of people since 2017. Get yours here.
2. Turn Your Phone Screen Red
Night shift mode or low blue light mode on your smart phone will not stop blue light affecting your sleep. At BLUblox we have tested these claims in a recent YouTube video using a lab grade spectrometer. Spoiler alert, these applications do not block all blue light so will not help stop blue light from affecting your sleep. The best hack for this is to turn your phone screen red, check out the article on how to do this here.
3. Stop Using Your Devices 2 Hours Before Bed
Studies have shown that if you use your smart phone, watch TV, or read from an e-reader right up until bedtime you will be disrupting your melatonin production and the blue light emitted from these devices will be affecting your sleep. Power down your digital devices two to three hours before bed and notice a huge improvement in your sleep.
4. Circadian Lighting
Did you know that studies have shown that blue light hitting your skin after dark can dial down melatonin production? We have blue light receptors in our skin called melanopsin which can detect blue light. There are two ways to combat this. Firstly, cover your skin with long clothing after dark but a better option is to use circadian lighting. We like Lumi Light Bulbs as they not only have no blue light in their Sleep+ model but they also have no flicker, low EMF and a huge life span. Red light post sunset can relax you and red light has been shown not to affect sleep negatively. Drop your high blue light bulbs and opt for Lumi Sleep+ after sunset instead. Avoid bulbs run off wifi and Bluetooth as these bulbs emit high EMF, flicker and EMF and flicker can also disrupt melatonin and negatively impact your sleep.
5. Sunrises
Sunrises and morning sun exposure has been shown to improve sleep later in the day. Starting your day with your eyes seeing the sunrise is exactly what our ancestors would have seen. It’s this light that entrains our circadian rhythms and keep our hormones in balance. Serotonin is produced under morning sunlight and in the absence of blue light after sunset serotonin mixes with tryptophan to produce melatonin.
Final Words
Does blue light affect sleep? This is 100% yes, and not in a good way. Blue light affects our sleep by disrupting our circadian rhythms and turning g off sleep hormone production. The good news is it’s an easy fix. By wearing blue light glasses after sunset that block 100% between 400 and 550nm, hacking your smart phone, limiting digital device use post sunset, using circadian friendly lighting after sunset and watching the sunrise you can stop blue light affecting your sleep.
For more information on blue light and its impact on our health and wellbeing and for the best blue light glasses please visit blublox.com
References
https://www.jneurosci.org/content/21/16/6405
https://pubmed.ncbi.nlm.nih.gov/11763987/
https://www.researchgate.net/publication/21258713_Green_Light_Attenuates_Melatonin_Output_and_Sleepiness_during_Sleep_Deprivation
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3047226/
https://www.nature.com/articles/s41598-017-16689-4