With the proliferation of digital devices that emit blue light, like smartphones, tablets, and computer screens, many people are concerned about how this artificial light exposure may affect our health. Blue light specifically has been implicated in disrupting our circadian rhythms and sleep cycles. This has led some to take measures to reduce their blue light exposure, especially before bedtime. One popular solution is to wear blue light blocking glasses. But do these special lenses really filter out blue light from screens and devices? Let’s take a closer look.
What is blue light?
Light is made up of different wavelengths across the visible spectrum. Blue light is the light with shorter, higher-energy wavelengths, ranging from 400-500 nm. It is emitted from natural sources like the sun, but also from artificial lights like LEDs and fluorescent bulbs, and digital screens. While blue light exposure during the day can have benefits like boosting alertness, mood, and reaction times, excessive exposure at night from our devices has been linked to disruption of our natural sleep-wake cycles. The concern is that blue light exposure suppresses melatonin production, the hormone that regulates sleep.
How do digital devices emit blue light?
LED (light-emitting diode) and OLED (organic LED) screens have become standard for most smartphones, tablets, laptops, and flat-screen TVs. While extremely energy-efficient, these displays emit significant amounts of blue light. Research has shown that evening exposure to blue light from screens can delay the release of sleep-inducing melatonin, making it harder to fall asleep. Effects on sleep can include taking longer to fall asleep, decreased sleep quality and duration, and daytime sleepiness. Chronic disruption of sleep cycles from blue light exposure has been associated with long-term health issues like depression, metabolic disorders, cardiovascular disease, and cancer.
Do blue light glasses block blue light from screens?
Specialized eyewear marketed as “blue light blocking glasses” claim to filter out the blue-violet wavelengths from digital screens to prevent eye strain and disruption of sleep cycles. But do they work as advertised? The lenses in these glasses are treated with optical filters or coatings that absorb and reflect portions of the visible blue light spectrum. Here are some key points about their effectiveness:
- Most blue light glasses block 70-90% of blue-violet light from 400-455 nm.
- They are less effective at filtering longer wavelength blue light from 460-500 nm.
- They do not block all blue light, as some wavelengths are still transmitted.
- Their filtering ability depends on lens material, coatings used, and manufacturing quality.
- Yellow-tinted lenses tend to block more blue light than clear or rose-colored ones.
- Lens opacity plays a role, with more opaque lenses blocking more blue light.
- Not all products advertising as blue blockers provide sufficient filtering capabilities.
Overall, blue light glasses can significantly reduce, but not completely eliminate, blue light exposure from screens. The level of blue light filtration can vary considerably between different brands and models. When shopping for blue light glasses, look at the specific wavelength ranges blocked and percentage of blue light filtered. Also consider lens opacity, as more opaque lenses tend to block more blue light.
Do they reduce digital eye strain?
Many people report that wearing blue light blocking glasses make screen use more comfortable and reduce symptoms of digital eye strain, like eye fatigue, headaches, dry eyes, and blurred vision. By filtering out the highest energy visible light, they can take the “edge off” the blue-rich light from device displays. This may decrease visual discomfort and eye fatigue associated with prolonged use of smartphones, tablets, and computers. However, blue light is just one factor in digital eye strain. Proper viewing distance, frequent blinking, appropriate font sizes, and using screen filters can also help minimize eye discomfort.
Do they help you sleep better at night?
Some studies suggest that wearing blue light blocking glasses for 1-2 hours before bedtime may improve sleep quality and duration. By reducing blue light exposure in the evening, melatonin release can occur at the appropriate time to prepare the body for sleep. In a small clinical trial, adults who wore blue blockers while using devices at night reported less insomnia, improved sleep quality, and better mood. However, not all studies have found significant improvements in sleep by wearing these glasses before bed. They may provide some benefits for those sensitive to evening blue light exposure, but results can vary individually.
Other considerations
Here are some other factors to keep in mind regarding blue light blocking glasses:
- They may alter color perception and distort colors seen through the lenses.
- Some report headaches, nausea, or dizziness, especially early on as eyes adjust.
- Darker lenses can reduce visual acuity indoors and make night driving difficult.
- Not intended to substitute for medical advice for sleep issues.
- People react differently based on their sensitivity to blue light.
Types of blue light glasses
Blue light blocking glasses are available in different lens styles, tints, and materials. Here is an overview of some common options:
| Type | Description | Pros | Cons |
|---|---|---|---|
| Yellow-tinted | Yellow lens absorbs more blue light, provides highest blue light filtration. | Great nighttime blue light blocking. Improves contrast. | Distorts color perception the most. |
| Amber-tinted | Orange/amber lens also blocks considerable blue light. | Good blue light protection. Preserves more color accuracy. | May not block as much blue light as yellow. |
| Clear lens with coating | Nearly colorless lens treated with blue light filtering coating. | Blocks blue light with minimal color distortion. | Can be less effective than tinted lenses. |
| Photochromic | Lens darkens when exposed to UV light outdoors. | Adjusts visible light transmission for indoor and outdoor use. | Does not adapt to device screens without UV light. |
| Mirrored coating | Partially reflective lens coating filters more light. | Increased blue light blocking. Also offers UV protection. | Reflective lens limits eye contact. |
Within each category there is variation in lens darkness, opacity, and precise color that affects blue light filtering capabilities. Some general guidelines are that more opaque lenses block more blue light, and yellow/amber lenses provide greater blue light filtration than rose-colored or clear lenses.
Do blue light glasses work?
Here is a summary of the effectiveness of blue light blocking glasses:
- They do not eliminate all blue light from digital devices but significantly reduce exposure.
- Amount of blue light filtered depends on specific lens material and quality.
- Best at blocking blue-violet wavelengths 400-455 nm.
- Some but more variable blocking of longer blue wavelengths up to 500 nm.
- Can provide mild to moderate improvement in sleep quality.
- May help with reducing digital eye strain when using devices at night.
- Large individual variability in response to these glasses.
- Not a substitute for good sleep hygiene practices.
While not a panacea, blue light glasses can be a helpful tool for some people as part of an overall strategy to improve sleep, eye comfort, and wellbeing in our increasingly screen-centric world. Those bothered by blue light at night may find them beneficial, but they should be viewed as just one piece of the puzzle.
Other ways to reduce blue light exposure
Here are some other tips to limit blue light in addition to wearing blue light blocking glasses:
- Avoid screen use 1-2 hours before bedtime.
- Install apps to filter blue light on devices in the evening.
- Reduce screen brightness at night and use dark mode.
- Wear computer glasses with an anti-reflective (AR) coating.
- Sit at least 18 inches from screens.
- Use e-readers or switch devices to print in the evening.
- Dim indoor lighting in the evening.
- Cherry-red bulbs or salt lamps emit warmer low blue light.
Conclusion
Specialized glasses claiming to block blue light can filter out a significant portion, but not all, of the blue light wavelengths emitted from digital screens. They may provide mild to moderate benefits for sleep and eye strain for some individuals sensitive to blue light exposure at night. However, simply wearing these glasses is not enough – practicing good sleep hygiene by limiting evening screen time, keeping rooms dark, and maintaining consistent sleep and wake times also remains essential. While not necessarily a cure-all, blue light glasses can be a helpful addition to an overall healthy lifestyle when used appropriately.
