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Does Blue Light Really Affect Your Sleep?

Does Blue Light Really Affect Your Sleep?
Written by Matthew Hermann

Let’s face it, 2020 shoved a new level of anxiety in our faces. Prior to the pandemic, we could at least rely on social interactions to help alleviate work or school-related stressers. As soon as the in-person opportunities halted, our eyes shifted from friendly faces to digital discussions. As of June 2020, screen time nearly doubled across all teen-aged groups compared to pre-pandemic screen times1. From careers to entertainment, the amount of blue light we have been exposing ourselves to since the pandemic has significantly increased. At the same time, more than 50% of Americans report increased difficulty with sleeping since the start of the pandemic2. This is sometimes lovingly referred to as COVIDsomnia.

 

Which leads us to the question…is the increased exposure to blue light impacting sleep?

 

What is blue light?

In its simplest form, light is a form of energy that travels in waves. Going in order of the light spectrum from red to violet, longer waves are at the beginning of the spectrum (red) and become shorter and shorter towards the end of the spectrum (violet).

Blue light has a shorter wavelength, meaning it has a higher frequency, meaning it has more energy.

These are the light waves emitted by computers, smartphone screens, iPads, e-readers, and even some LED bulbs used for lamps. In today’s industrial society, blue light is everywhere. Sunglasses aren’t the only cool eye protection gear we can sport around these days. Now we can wear “blue light blockers” while staring at our screens all in the name of health.

Does blue light actually affect sleep?

Let’s start by looking at life without electronic devices in existing preindustrial communities. Dr. Gandhi Yetish, who is a professor for the Department of Anthropology at the Univeristy of New Mexico, investigated sleep patterns under natural conditions in three preindustrial societies3. These groups were tribal communities located in Tanzania, Bolivia, and Namibia. Electricity does not exist in these societies. Because of this, they live a lifetime of exposure to only natural lighting from the sun. Researchers gave the participants Actiwatch-2 devices to measure sleep parameters during this study. They found that each group had similar sleep time, which was between 5.7 and 7.1 hours.

Okay hang on, this is fewer than the recommended 8 hours of sleep we all hear about! That must mean they get crappy sleep, right?

It turns out they get great sleep! When Dr. Yetish and his team interviewed each tribe with a translator, they asked them about their experience with insomnia. No one in either tribe understood what they were asking. None of these preindustrial societies have a word for insomnia. Researchers then explained the concepts of sleep difficulties. Only 5% of the participants reported occasionally having difficulty with falling asleep, and 9% noted some difficulty with staying asleep. Finally, only 1.5-2.5% of the participants reported chronic problems with sleeping.

Compare that to the 10-30% chronic insomnia rate reported in industrial societies, and we can see who the clear winner is in sleep success. This may be the one situation where if you snooze, you in fact do not lose4.

There are a couple of possible explanations for their dreamy sleep triumphs:

Natural light exposure: Other researchers have pointed to light as a major contributor to human sleep and circadian rhythm control. This is because light has an effect on the melanopsin system, which basically means light helps to control when and how much melatonin our own body produces (the pineal gland produces melatonin for us5). In essence, the darker it gets, the more melatonin our pineal gland releases.

Shorter nights: Each preindustrial society studied is close to the equator. Because of this, their winter nights are not as long as Western Europe. Historical evidence shows that Western Europeans would often sleep in two major intervals during the night, usually just peacefully lying in bed wide awake in the middle of night waiting to fall back asleep with longer hours of darkness. This is no longer seen in the northern latitudes because of electric lights and temperature control.

So, without man-made lights to distract these socieities, better sleep at shorter durations is achieved. 

Okay, but HOW does blue light actually affect sleep?

A recent review of articles researching the impacts of light and the human circadian rhythm found that at least two hours of exposure to blue light in the evening suppresses melatonin secretion, which then impacts the circadian rhythm6. This was not seen with other lights with longer waves, like green light or red light. There is a part of our brain that’s known as the “master circadian clock” known as the suprachiasmatic nucleus (SCN).  The SCN organizes hormone secretion, such as melatonin, and is synchronized by light-dark transitions. If there’s a disruption in the light-dark transition (such as staring at all of those Instagram photos or TiKTok videos), then the SCN is disturbed and just waiting to release the melatonin once light is no longer present.

Even using e-readers to read your book at night can negatively impact your sleep cycle through melatonin suppression. A study conducted at Brigham Health found that “Participants reading a light-emitting e-book took longer to fall asleep and had reduced evening sleepiness, reduced melatonin secretion, later timing of their circadian clock, and reduced next-morning alertness.”7

What can you do to reduce the effects of blue light on sleep?

While there is not “secret formula” that works for everyone, there are simple steps you can take to get better sleep despite being surrounded by electronics and artificial lights all day.

  1. Download or activate an app on your phone that blocks blue light. Our favorite app is Blue Light Filter by Night Mode. You can install a blue light filter on your computer, as well.
  2. Create a sleep routine and stick to it. Do you want to be asleep by 10:00? Then charge your phone in another room at 9:00 or 9:15 and begin your bedtime routine!
  3. Take low-dose melatonin supplements. We can’t avoid being surrounded by blue light all day. Give your internal circadian clocks a small boost by trying our 1.5 mg melatonin strip.
  4. Swap out your lamp bulbs for red or orange bulbs. If you like to relax in bed with a book (preferrably paper and not ebook), try reading under a light that isn’t going to suppress your melatonin secretion. Red or orange lights have been shown to actually help induce sleep. 

 

REFERENCES

  1. Johnson, J. (2020, November). S. Kids & Teens With 4hrs+ Screen Time Beofre and uring COVID-19 Pandemic 2020. Statista.
  2. American Academy of Sleep Medicine. (2021, April 12). Americans Continue Struggling For a Good Night’s Sleep During the Pandemic.
  3. Yetish, G., Kaplan, H., Gurven, M., Wood, B., Pontzer, H., Manger, P. R., Wilson, C., McGregor, R., & Siegel, J. M. (2015). Natural sleep and its seasonal variations in three pre-industrial societies. Current biology : CB25(21), 2862–2868.
  4. Bhaskar, S., Hemavathy, D., & Prasad, S. (2016). Prevalence of chronic insomnia in adult patients and its correlation with medical comorbidities. Journal of family medicine and primary care5(4), 780–784
  5. Santhi, N., Thorne, H.C., van der Veen, D.R., Johnson, S., Mills, S.J., Hommes, V., Schlangen, L.J.M., Archer, S.N., & Dijk, D.J. (2011). The Spectral Composition of Evening Light and Individaul Differences in the Suppression of Melatonin and Delay of Sleep in Humans. Journal of Pineal Research. 31(1): 47-59.
  6. Tähkämö, L., Partonen, T., & Pesonen, A. K. (2019). Systematic review of light exposure impact on human circadian rhythm. Chronobiology international36(2), 151–170. https://doi.org/10.1080/07420528.2018.1527773
  7. Chang, AM & Czeisler, CA. (n.d.) Beware of Blue Light Before Sleep. Brigham Health Hub. https://brighamhealthhub.org/beware-of-blue-light-before-sleep

 

Last updated July 20, 2021 by Matthew Hermann