What does the science say about blue light glasses?

Blue Light Blocking Glasses have become an important accessory for those concerned about blue light exposure. Brands across fashion, wellness and optical markets are all adding blue light blocking glasses to their product ranges, making broad claims about their effectiveness across a range of benefits.

How much evidence is there to support these claims? Including our claims here at Sentient? Is there scientific evidence to support the marketing claims? Or is it more vibes and hope for the best kind of approach?

Let’s sort facts from marketing fiction.

1. What frequencies are considered blue light?
2. How does natural blue light affect us?
3. When does blue light become problematic?
4. Does blue light affect sleep?
5. Why Blue Light Glasses were developed
6. Can Blue Light Glasses improve sleep?
7. Is blue light responsible for Digital Eye Strain
8. Do Blue Light Glasses protect the retina

What frequencies are considered blue light?

The human eye is able to detect light between 380 to 700 nanometres. Blue light is considered between 380 to 500 nanometres.

How does natural blue light affect us?

Blue light plays an important part in regulating our physiology.

The majority of blue light we encounter comes from natural sunlight. A short period outdoors exposes the eyes to significantly more blue light than many hours in front of an electronic screen.

During the day, blue wavelengths help regulate the body's circadian rhythm by suppressing melatonin production, increasing alertness and supporting normal sleep-wake cycles. 

From the Cleveland Clinic melatonin explainer article;

“Melatonin affects cells in your brain’s hypothalamus. It tells your hypothalamus it’s time to slow activity down for the day. Once it gets the message, your hypothalamus dials back the functions it controls — like your body temperature, blood pressure and mood — to get you ready for sleep.

In your eyes, melatonin changes your retinas to get ready for rest and being less active. Melatonin helps your retinas become less responsive to light, which helps you wind down and feel less alert. When there’s more natural light the next morning, your retinas automatically become more active and your body stops releasing as much melatonin.”

I’ve seen this phrased as our ‘spectral diet’, which is a nice term to summarise the importance of light in our overall health.

When does blue light become problematic?

Established in an animal study in 1970 and then in humans in this study in 1980, we know bright artificial light suppresses our melatonin levels, which affects the bodies natural get-ready-for-sleep processes. 

More recent studies, including this study in 2010, established that blue light frequencies are the cause of decreased melatonin. The 2010 study features this key quote from the abstract;

“Results showed-that, as expected, only the blue light reduced nocturnal melatonin.” 

-- From "The effects of red and blue lights on circadian variations in cortisol, alpha amylase, and melatonin"

Does blue light affect sleep?

The short answer is yes, blue light can affect sleep.

More specifically, blue light directly affects the sleep preparation process by lowering the body's natural creation of melatonin.

Why Blue Light Glasses were developed

With the proliferation of electronic and digital screens, along with LED and fluorescent lighting, the amount of blue light battering our eyes after dark has increased exponentially over the last three decades.

Blue light filtering lenses were designed to combat the blue light that is now omnipresent in our daily lives.

Can Blue Light Glasses improve sleep?

There are numerous studies that have concluded that blue light glasses can improve melatonin production and sleep.

Blocking nocturnal blue light for insomnia: A randomized controlled trial (2017)

Protective effect of blue-light shield eyewear for adults against light pollution from self-luminous devices used at night (2016)

Blue Blocker Glasses as a Countermeasure for Alerting Effects of Evening Light-Emitting Diode Screen Exposure in Male Teenagers (2014)

Blue blocker glasses impede the capacity of bright light to suppress melatonin production (2006)

Amber lenses to block blue light and improve sleep: A Randomized Trial (2009)

Wearing Blue-Blockers in the morning could improve sleep of workers on a permanent night schedule: A Pilot Study (2010)

Is blue light responsible for Digital Eye Strain

Digital Eye Strain, also referred to as Computer Vision Syndrome, is a genuine and increasingly common condition affecting people who spend prolonged periods using digital devices. Symptoms often include tired eyes, blurred vision, headaches, difficulty maintaining focus, dry eyes and discomfort in the neck and shoulders.

Although blue light has  been presented as a cause of digital eye strain, current evidence indicates that these symptoms arise largely from the way people use digital devices rather than from the light they emit. Concentrating on nearby objects for extended periods reduces blink frequency, causing tears to evaporate more quickly and increasing dryness. Long periods of sustained focusing place continuous demands on the eye's accommodative system, while poor posture, glare and suboptimal workstation ergonomics further contribute to discomfort.

In other words, the problem is generally prolonged screen use itself rather than blue light.

Individual clinical trials have reached similar conclusions. In this double-masked randomised controlled trial from 2021, participants completed prolonged computer-based tasks while wearing either blue light filtering lenses or visually identical clear lenses. Researchers assessed eye strain, visual fatigue, comfort and reading performance.

The study found no clinically significant improvement associated with blue light filtering lenses.

Participants wearing blue light glasses experienced levels of visual comfort and eye strain that were comparable to those wearing standard clear lenses. 

Do Blue Light Glasses protect the retina

Perhaps the most significant marketing claim surrounding blue light glasses is that they protect the retina against long-term damage or prevent age-related macular degeneration.

Current clinical evidence does not support this claim.

What do we say here at Sentient about the benefits of our blue light glasses

In our minds, blue light blocking should be assessed in two separate categories. 

Category 1 - do the lenses actually block the light they claim to

Our lenses are high quality lenses by a reputable manufacturer, fully lab tested and reported against Australian, American and European lens standaards.

Category 2 - the health benefits of blocking blue light

There is clear scientific evidence supporting melatonin suppression by blue light;

1. Bright light suppresses the body's production of melatonin
2. Blue light is the part of the light spectrum that has the negative effect

Evidence is still lacking around blue light blocking glasses improving Digital Eye Strain.

Evidence is also lacking around blue light damaging the physical health of eyes inlcuding macular degeneration and retina damage.

We (Todd and I) have always agreed on one thing in our partnership; honesty and transparency. We aren't interested in making crazy claims about any aspect of our glasses, especially health related claims. People's health is a serious foundation of our brand, not a bunch of throw away dot points on a sales page.

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