Blue-Light Blocking Glasses: Do they actually work?



Everyone tells you not to sit on your phone or watch TV 30mins to an hour before bed because it’s bad for your eyes.. But why is this? What is the reason for it?


It’s all good, I did some research for you. And here it is.


Hormones – the stuff that literally keeps our system functioning - released via the pineal gland in the brain in a 24-hour circadian rhythm. (Circadian means “recurring naturally on a twenty-four-hour cycle, even in the absence of light fluctuations”).


The main hormone that triggers sleep is melatonin.


During the day-time, our circadian rhythm and what is known as the circadian pace-maker, is fed by light coming in to our eyes, in particular retinal cells. This information tells our brain and most importantly the pineal gland to secrete certain hormones that keep us alert.


These retinal cells in our eyes show maximum sensitivity to short wavelengths of light, particularly in the blue region of the light spectrum. This region is known commonly as ‘blue light’.


Electronic screens are often rich in ‘blue light’, meaning that even though the sun has gone down, watching TV or sitting on your phone at night tricks the brain to think that it is still day time and you should be awake! This delays and weakens the release of melatonin and contributes to decreased evening sleepiness and a dysfunctional sleep-wake cycle.


Now I’m sure you’ve seen and heard about ‘blue-light blocker glasses’ and the claims that they can reduce the strain on the eyes caused by blue light emitted from digital screens.


So, do they actually work?


Here is a study that looked into blue light glasses:


Effects of pre-bedtime blue-light exposure on ratio of deep sleep in

healthy young men.


This study aimed to investigate the effects of pre-bedtime blue-light exposure on ratio of deep sleep and sleep quality.


In this study, 11 healthy young men were exposed to three conditions for 1 h before

Bedtime whilst reading:

1) incandescent light

2) blue-light

3) blue-light with blue-light-blocking glasses on


The following morning, subjective sleep quality was measured using the OSA sleep inventory. Sleep time, ratio of sleep, ratio of deep sleep, and body movements during sleep were measured using a mat sleep-scan (L- 504; Tanita Corp., Japan) and an ambulatory portable sleep study system (S-140; Fukuda Denshi Co. Ltd., Japan).


Results = Ratio of deep sleep was significantly decreased in the blue-light exposure group compared to the groups with incandescent light and blue light-blocking glasses (p < 0.01).


There were no differences noted in sleep time, body temperature or body movements among the three groups. There were no significant differences in all three groups on sleep quality subjectively. These results suggest that blue-light exposure affects sleep quality by reducing the ratio of deep sleep.


There were of course some limitations in this study, one main one being the sample size of 11 participants. Therefore more robust studies looking into blue light blocking glasses are needed. This brings me to the next study that is in development.


Sleep quality is one thing, but did you know that there is evidence out there to suggest that circadian misalignment (such as using too much tech at night), is associated with an increased risk of:

- Obesity

- Diabetes

- Depression

- Ischaemic heart disease

- Stroke

- Cancer

- Age-related macular degeneration (AMD)


This might seem out there, but there is a large prospective (meaning looking into the future at the results, for example in 20 years) study going on involving up to 1000 participants with cataracts that will be randomly allocated to using intraocular lenses (IOLs) or blue-light blocking IOLs at a ratio of 1:1.

Their primary outcomes are:

- Mortality

- Cardiovascular disease

- Cancer

- AMD


These primary outcomes will be followed until 20 years after eye (cataract) surgery. We might be waiting a while for those results, so in the mean time if you are someone who loves getting home from work and sitting in front of a screen to wind down, maybe its worth looking into them.


I myself use blue-light blocking glasses particularly when I get home at night. They are relatively inexpensive, with the pair I bought costing me $65 from Baxter Blue. If I have a report to write on the laptop, then I will chuck them on as well. I’ve noticed decreased frequency and severity of headaches associated with looking at my phone, laptop or TV screen.


So my question to you is, why not give them a try? It could be a simple and relatively cheap option to help with sleep quality. Let’s face it, we could all do with better sleep.



References:

Ishizawa, M., Uchiumi, T., Takahata, M., Yamaki, M., & Sato, T. (2021). Effects of pre-bedtime blue-light exposure on ratio of deep sleep in healthy young men. Sleep Medicine, 84, 303-307.


Moderie, C., Van der Maren, S., & Dumont, M. (2017). Circadian phase, dynamics of subjective sleepiness and sensitivity to blue light in young adults complaining of a delayed sleep schedule. Sleep medicine, 34, 148-155.


Nishi T, Saeki K, Obayashi K, et al

The effect of blue-blocking intraocular lenses on circadian biological rhythm: protocol for a randomised controlled trial (CLOCK-IOL colour study)

BMJ Open 2015;5:e007930. doi: 10.1136/bmjopen-2015-007930


Moderie, C., Van der Maren, S., & Dumont, M. (2017). Circadian phase, dynamics of subjective sleepiness and sensitivity to blue light in young adults complaining of a delayed sleep schedule. Sleep medicine, 34, 148-155.


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