A growing number of brands are selling blue light blocking glasses, marketing them as the solution to poor sleep and strained eyes. You’ve probably seen them before – those bright orange, laboratory-style glasses.
They certainly look as if they must be doing something, but are they?
This article will take a look at where these claims have come from, the science behind the orange, and whether we should all be wearing them.
The theory behind why these glasses should work is, to me, quite interesting (but perhaps that's because I'm a bit of a physiology nerd...)
The theory is also pretty easy to grasp, and sounds quite logical. Perhaps this is at least partly responsible for their success.
Let's explore the theory...
The science behind these glasses is based on the idea that certain wavelengths of light (the ones responsible for the colour blue) have a particularly strong influence on our body clock, also called our circadian rhythm.
This is because blue light acts as a signal of day-time, and thus helps our brain to know when we should be awake and when we should be sleeping. In this way, the regular rising and setting of the sun acts like the conductor of the orchestra that is our body.
For most of human history, light from the sun has been the only form of light to influence our brain and body. Over the last few centuries, however, the increasing presence of artificial light (coming from our lightbulbs, laptops, TVs, and telephones) has extended the length of the day in which we are exposed to light.
This has impacted our daily lives in many ways. One important way is that our environment stays lighter for longer, and thus gives a signal of daytime to our bodies late into the night. The second effect is that, since we can turn off the lights at the flick of a switch, we can create a sudden transition from day to night, which is different from the slow gradual setting of the sun our bodies are used to.
This can confuse our brain and body clock, leading to desynchrony between the systems of the body - like an orchestra that has lost its conductor. As a result, different processes can get out of whack, and lead to all sorts of problems - the major one being disrupted sleep. And since sleep is a central pillar in the foundations of a healthy life, poor sleep can disrupt things like memory, mood, and weight management.
There is growing evidence that increased screen time is leading to reduced sleep quality and length, as well as increased tiredness, especially in youngsters looking at screens late at night. Especially during lockdown, whether it's Netflix or a zoom quiz, screens have become a core part of our evening.
It’s also been suggested that the glare from these devices tires out our eyes, leading to eye strain.
So, where do the glasses come into this?
Scientists wondered whether blocking blue light from our eyes would mean we’d be able to trick the brain into thinking it's night, even with the lights on… along came the blue-light blocking glasses!
These glasses have been marketed as products that will help alleviate eye strain & fatigue, and protect the eye from damage, as well as improve sleep quality. However, these are big claims, so it's important that we check whether they are true.
What does the research say?
Well, there are a couple of important things to consider. Firstly, there is a clear commercial interest in this research since positive results will easily translate to market value. For this reason, it is important to identify who is funding the studies. However, one systematic review (which is a type of study that collates lots of other studies) found that 71% of the trials it looked at did not report the funding sources.
The second is that you cannot test for the placebo effect in studies using these glasses. The reason for this is that the person wearing the glasses will always know they are wearing the glasses - because everything will be tinted orange! This means that the placebo effect could be behind any benefits we see.
Many brands sell clear, un-tinted glasses, or glasses that are marginally tinted. However, these still let most blue light through, and since blue-light is the thing we’re trying to block, it’s hard to imagine these have measurable benefits.
Even with bright orange glasses, however, the evidence is pretty weak. Most studies have not shown significant benefits, and even in those that have, the benefits were small.
Furthermore, the small improvements that were seen in these few studies were primarily observed in more vulnerable populations, like those with sleep/psychiatric disorders, including insomnia, bipolar disorder, delayed-sleep phase syndrome, and ADHD. In healthy individuals, it seems the benefits are less clear.
There is one scenario, however, where it seems there may be a benefit. Say you’ve been in the dark for a while and your body has started slowing down for the night… if you then re-expose yourself to light (perhaps by looking at your device), wearing these glasses may limit you’re the shock your brain receives, and thus not impact the remaining hours of sleep.
What can we take away from this?
Whilst there are no obvious benefits for a healthy person, there have also been no identified negative implications of their use. This means that whilst you probably won’t benefit from using them day-to-day, there’s no harm in trying them.
It is important to bear in mind though that if poor sleep and eyestrain are the problems, then there are many other better (cheaper) solutions...
Tips for better sleep & healthier eyes...
1. Download f.lux – a free program for your computer that reduces the amount of blue light coming from your screen after a certain time of the day
2. When looking at screens throughout the day, especially ones close to your face like laptops and phones, remember the 20.20.20 rule – every 20 minutes, look at something 20 metres away for 20 seconds. These regular small breaks for your eyes will help to reduce eye strain.
3. Try to get as much natural light during the day as possible – this strengthens the oscillations of your body clock helping you be more awake during the day and sleep better during the night.
4. Be more conscious of screen time in the evenings – set limits on how late you're allowed to look at your phone in the evening, or how long you will stay on your computer.
5. Avoid overly stimulating activities – whether it's exercising or watching scary movies, activities that require your brain to be switched on may limit the quality of your sleep (however, there may be an exception to this...!)
I give blue-light blockers a 3/10
Key sources & further reading:
Downie LE, Wormald R, Evans J, et al (2020) Analysis of a Systematic Review About Blue Light–Filtering Intraocular Lenses for Retinal Protection, JAMA Ophthalmology, 137(6), 694-7 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6684842/
Hale L, Kirschen GW, LeBourgeois MK, et al. (2018) Youth Screen Media Habits and Sleep: Sleep-Friendly Screen Behavior Recommendations for Clinicians, Educators, and Parents, Child and adolescent psychiatric clinics of North America, 27(2), 229-245 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5839336/
Lawrenson JG, Hull CC, Downie LE (2017) The effect of blue‐light blocking spectacle lenses on visual performance, macular health and the sleep‐wake cycle: a systematic review of the literature, Ophthalmic and Physiological Optics, 37(6), 644-54 https://onlinelibrary.wiley.com/doi/full/10.1111/opo.12406
Shechter A, Quispe KA, Barbecho, et al. (2020) Interventions to reduce short-wavelength (“blue”) light exposure at night and their effects on sleep: A systematic review and meta-analysis, Sleep Advances, 1(1), zpaa002 https://academic.oup.com/sleepadvances/article/1/1/zpaa002/5851240
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