Blue light blocking glasses for everyone!
Verging on Oprah-esque style, I have recommended blue light blocking glasses to many over the past couple years.
I’ve blogged about their benefit for sleep, bought them for my kids and personally wear them most nights.
Then one day I wondered:
Do these glasses actually improve sleep?
--> And if they do, are they working by the mechanism they say they are?
So off to PubMed I went. I did not find a lot of evidence to answer my specific questions but what I found is promising.
Check it out.
If you aren’t familiar with blue light blocking glasses, here is the 411.
First off, what is blue light?
&
Why would you want to block blue light ?
On the visible light spectrum, blue light is a high energy light with a “short” wavelength that exists between 400-495 nm.
The sun is our main source of blue light but that is not what I'm discussing. I'm talking about artificial blue light, the light arises from our technological devices. These light sources, also known as light-emitting diodes LEDs, include smartphones, tablets, computer screens and flat screen tv’s.
Several studies have demonstrated that the use of blue light-emitting devices close to bedtime negatively impact sleep. (1)
How does blue light impact sleep?
We have photoreceptors in our retinas that transmit light information to the suprachiasmatic nucleus (SCN) in the hypothalamus region of your brain. The SCN is considered the master regulator of our circadian clock. In regards to sleep its main function is the regulation of melatonin secretion from the pineal gland. Melatonin, known as the darkness hormone, regulates the sleep-wake cycle namely by initiating sleepiness.
Our circadian clocks have evolved to follow the light-dark cycle of our world. But our world has changed. In recent years our evening exposure to blue light has increased exponentially as we spend more time "connecting" with our devices.
Working similar to jet lag, the blue light causes a shift (or delay in our clock) by suppressing the release of melatonin. When this happens we don’t feel sleepy until later and a "phase shift" of our circadian rhythm occurs. This shift affects our sleep health and potentially has more negative effects than just a later bedtime. (2)
Does the evidence confirm this?
Several studies have confirmed that light exposure does effect sleep architecture. (3)
One study specifically showed a decrease in REM sleep due to phase shifting from evening exposure to eReaders (4)
It makes sense that if we’ve established that blue light negatively impacts sleep that either removing it or minimizing our exposure, by wearing glasses that block blue light would help sleep.
But does it?
TL;DR – The published data shows mostly subjective improvements in sleep. Thus far, there is minimal evidence of their impact on objective measures of sleep. More studies are needed verify that blue light blocking glasses help sleep by decreasing the suppression of melatonin release.
**At the end of the blog, find brief summaries on the 3 main studies focusing on sleep and blue light blocking (BB) glasses published at this time.**
What we know
BB glasses help subjective sleep quality, quantity and these effects might stem from preventing melatonin suppression.
BB glasses are a safe and inexpensive potential intervention for insomnia and for overall sleep health.
One week of BB use may not be enough to change the effects of blue light induced circadian shift (7)
Blue light potentially affects kids more than adults – even of shorter exposure duration (8) and kids/teenagers benefit from wearing BB glasses (7)
One study has shown that wearing BB glasses caused a reduction of melatonin suppression (7)
What we don’t know
We don’t know if the positive results we see in sleep after BB use are definitively due to prevention of melatonin suppression. We need more than one study. (7)
Multiple factors affect sleep quality. Current evidence suggests that there is an effect of wearing BB glasses before bed. We don’t know if that effect is significant when compared to other factors, which varies per individual.
Further Questions to Consider
Are there certain glasses that do a better job at filtering blue light? Does the shape of the lenses make a difference in the efficacy?
Do men and women respond differently to circadian shifting?
Are BB as effective as apps like flux? Would there be an additive effective if you used both?
Are there other advantages to wearing BB blockers (some proposed but not studied areas include: cancer prevention, PMS symptoms, obesity, insulin resistance, depression). We don’t have the answers yet but we should be asking the questions. Recommended reading (2)
Does your prior light history affect how well you will respond to BB glasses? Some research suggests that prior photic history can affect how well you adapt to phase shifting (9)
How much of an effect does artificial light in your home (not counting digital devices) affect your circadian rhythm? (10)
My Conclusion
On Amazon, a pair of BB glasses will cost you between $20-75 dollars. There are no known adverse effects so if you are willing make the investment you will likely reap some benefit.
This is especially relevant if you are exposed to blue light within 3-4 hours of your bedtime. That likely means the majority of you.
And last but certainly not least, don’t forget about your kids. How many of them are exposed to blue light 3-4 hours before their bedtimes?
MAKE THEM WEAR SHADES!
Study Summaries:
Study 1
In a randomized trial (n=20) of individuals wearing BB vs clear lenses results showed significant improvements of sleep quality in the BB group compared to controls. (5)
This study only looked at subjective measures of sleep quality.
They also found subjective improvements in mood
Study 2
A randomized control trial on 14 individuals with insomnia demonstrated improved sleep in in individuals wearing BB glasses for 2 hours before bedtime compared to controls (clear lenses). (6)
The sleep outcomes assessed were: Pittsburgh Insomnia Rating Scale (PIRS), Daily post-sleep questionnaire, Wrist actigraphy (motion detector)
Results showed improved scores on subjective measures of quality of life, and overall improvement in subjective reports of total sleep time, quality and soundness of sleep
Study 3
A comparative study looking at the effect of BB vs clear glasses on salivary melatonin levels, subjective sleepiness and vigilant attention before and after exposure to LED computer screens in a group of male teenagers. (7)
Outcomes showed a reduction in LED screen induced melatonin suppression in the BB group
Increase in sleepiness and decreased vigilance was observed in the BB glasses group.
Overall sleep stage characteristics were not significantly different between groups
REFERENCES
(1) E. D. Chinoy, J. F. Duffy, C. A. Czeisler, Unrestricted evening use of light-emitting tablet computers delays self-selected bedtime and disrupts circadian timing and alertness. Physiol. Rep. 6, e13692 (2018).
(2) Stevens, R. G., and Y. Zhu. 2015. Electric light, particularly at night, disrupts human circadian rhythmicity: is that a problem? Philos. Trans. R. Soc. B-Biol. Sci. 370:20140120.
(3) Wams EJ, Woelders T, Marring I, Van Rosmalen L, Beersma DGM, Gordijn MCM, Hut RA. 2017. Linking light exposure and subsequent sleep: A field polysomnography study in humans. Sleep. doi:10.1093/ sleep/zsx165
(4) Chang, A. M., D. Aeschbach, J. F. Duffy, and C. A. Czeisler. 2015. Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness. Proc. Natl Acad. Sci. USA 112:1232–1237.
(5) Burkhart K, Phelps JR. Amber lenses to block blue light and improve sleep: a randomized trial. Chronobiol Int. 2009 Dec; 26(8):1602-12.
(6) Shechter A, Kim EW, St-Onge MP, Westwood AJ. Blocking nocturnal blue light for insomnia: A randomized controlled trial. J Psychiatr Res. 2017;96:196-202.
(7) Van Der Lely S, Frey S, Garbazza C, et al. Blue blocker glasses as a countermeasure for alerting effects of evening light-emitting diode screen exposure in male teenagers. J Adolesc Heal 56(1):113-119.
(8) Sang-il L, Matsumori K, Nishimura K, et al. Melatonin suppression and sleepiness in children exposed to blue-enriched white LED lighting at night. Physiol Rep, 6(24), 2018, e13942
(9) Chang, A. M., F. A. Scheer, and C. A. Czeisler. 2011. The human circadian system adapts to prior photic history. J. Physiol. 589(Pt 5):1095–1102.
(10) Burgess, H. J., and T. A. Molina. 2014. Home lighting before usual bedtime impacts circadian timing: a field study. Photochem. Photobiol. 90:723–726.