Blue light isn’t just a buzzword — it has many doctors concerned over our long-term use of phones, computers, and tablets. But is blue light exposure that bad for our health, and how necessary are blue light blocking glasses? Here, we’ll discuss what you should know about blue light.
Sunlight is our biggest source of blue light, but long-term exposure from digital devices may have cumulative effects on our health.
Blue light is beneficial in moderate doses. It regulates sleep, boosts brain function, and aids other important processes in the body.
Excessive blue light exposure, particularly before bed, can disrupt sleep and potentially increase the risk of eye diseases.
Blue light glasses can help you sleep better, but may not improve symptoms of eye strain or reduce your risk for eye diseases.
What is blue light?
Blue light, also called high-energy visible light, is a color in the visible light spectrum. You may know the colors as red, orange, yellow, green, blue, indigo and violet.
These colors comprise white light. Red light has a longer wavelength and lower energy, while blue light has a shorter wavelength and higher energy. Visible light makes up a small portion of the electromagnetic spectrum, including ultraviolet (UV) rays, X-rays, gamma rays, infrared light, microwaves, and radio waves.
Common blue light sources
Blue light comes from many sources:
- Sunlight (by far the largest source of blue light; about 100,000 times more)
- Fluorescent lights
- Light-emitting diodes (LEDs)
- Smartphones and tablets
Is blue light always bad for your health?
In moderate amounts, blue light yields several health benefits:
- Regulates circadian rhythm (sleep-wake cycle)
- Boost mood
- Improves sleep quality
- Promotes alertness
- Aids memory and cognitive function
- Regulates metabolism
During the day, some sunshine can provide the blue light we need. The problem arises when we are exposed to blue light later in the day. At night, our brains release melatonin, a hormone that helps your body know when to sleep. Doctors also believe melatonin regulates menstrual cycles, prevents neurodegenerative conditions (like Alzheimer’s disease), and plays a role in other bodily functions.
Using digital devices before bed suppresses melatonin, which can cause problems such as:
- Disrupted sleep cycle and poor sleep
- Chronic fatigue and feeling tired during the day
- Higher risk of cancers, heart disease, reproductive issues, gastrointestinal disease, diabetes, obesity, depression, and neurodegenerative diseases
Although experts don’t know what constitutes “too much” blue light exposure, a good recommendation is to limit blue light exposure to two to three hours before sleep.
Blue light and your eyes
In addition to sleep and overall health, blue light can affect your eyes. One concern is that the proximity of digital devices to our eyes and long hours of screen time can expose us to unhealthy levels of blue light.
The cornea is the clear covering in front of the eye that helps you see clearly. Blue light passes through the cornea and reaches the lens and retina inside the eye. The lens helps to focus light while the retina gathers visual signals sent to the brain. Chronic and high levels of exposure to blue light (such as spending significant time outdoors) can increase your risk of eye diseases:
- Cornea. Blue light can damage cells in the cornea, leading to inflammation and dryness of the ocular surface.
- Cataracts. When the lens absorbs blue light, it can cause clouding and yellowing of the lens. Over time, your vision becomes blurry as the cataracts progress.
- Age-related macular degeneration. This disease of the macula (central part of the retina) affects your ability to see clearly. Studies show that intense blue light causes damage to the macula and retina.
Blue light is also associated with symptoms related to prolonged screen time, which is called digital eye strain:
- Blurry vision
- Double vision
- Dry eyes
- Eye strain
However, research shows conflicting evidence as to how much blue light affects these eye symptoms, if at all. Some experts believe uncorrected vision problems and poor workstation ergonomics are more significant factors.
Blue light coating in glasses
Even though we get far more blue light from the sun than from phones or computers, many people spend more time on their screens than outdoors. A blue light coating is an optional treatment you can add to your glasses to filter out some blue light. Most blue light treatments block 10% to 40% of blue light, although some specialty lenses (such as gaming glasses) can block higher amounts. The higher the percentage, the more yellow or amber the tint appears.
However, there’s some debate over the benefits of blue light coating. Studies show that using blue light glasses, especially before bed, can help you fall asleep faster and improve sleep quality. What remains unclear is whether blue light coating reduces your risk for eye diseases and digital eye strain.
Overall, most experts agree that blue light glasses are safe and may provide some sleep benefits. You can use these glasses when viewing your digital devices.
If you’re experiencing digital eye strain, blue light glasses may not solve your problems. Consult your optometrist to find out if you have other vision or eye issues that may need treatment.
- BMJ Open Ophthalmology. Digital eye strain: prevalence, measurement and amelioration.
- Cleveland Clinic. Melatonin.
- International Journal of Ophthalmology. Research progress about the effect and prevention of blue light on eyes.
- Journal of Psychiatric Research. Blocking nocturnal blue light for insomnia: A randomized controlled trial.
- Review of Optometry. Living With Blue Light Exposure.