What Are Blue-Light-Blocking Glasses and Do They Work?

If you are reading this article in the evening on your phone or computer, you are likely negatively affecting your sleep quality. A growing number of studies have reported recently that blue light exposure from smart devices and computers prior to bedtime may have a negative impact on sleep latency and overall sleep quality. These findings gave rise to a potential solution, or as many call it, a biohack — blue-light-blocking glasses.

The science is not conclusive on their efficiency, but some scientists say blue-light-blocking glasses may be helpful for night-shift workers or those who have a sleep disorder. How does light, particularly blue light, impact human physiology, and why this modern environment is taking a toll on sleep? Do blue-light-blocking glasses work? We did some digging and interviewing to find out.

Light and sleep

Throughout evolution, the human body learned to adapt to the daily cycle of the sun rising and setting. This natural phenomenon has been a strong cue to when humans would go to sleep and wake up. Similar to temperature, light is another zeitgeber to how the human body activates and inhibits the release of hormones — melatonin (sleep hormone) and cortisol (stress hormone).

In an interview with HealthNews, sleep psychologist Dr. Dan Ford explained that humans possess a 24-hour biological rhythm, or circadian rhythm, that governs their level of alertness throughout the day. “The ‘master biological clock’ that governs this rhythm is located in an area of the brain called the ‘suprachiasmatic nucleus,’ or SCN,” he said. While the 24-hour rhythm will maintain itself independent of any external influence, the master clock is designed to take timing signals from the environment to help us adapt to our surroundings. “The most potent timing signal is a bright light, with blue spectrum light being the most potent,” Dr. Ford noted.

What is blue light?

Blue light is a short wavelength light, measured between 450–495 nanometers. While it is part of natural sunlight, electronic devices such as smartphones, laptops, and tablets also emit blue light.

Therefore, blue light is not always bad — but the timing must be right. For example, bright light from the morning sun is essential for resetting one’s circadian rhythm and signaling the brain that it’s time to wake up, release cortisol, be alert, and kick-start the metabolism. On the other hand, blue light at night paints a different picture.

How blue light affects sleep

When the SCN is exposed to blue light in the evening, it may trick the brain into thinking it’s daytime.

A study of 16 healthy adults, ages 19–27, examined the impact of blue light exposure and melatonin release. Researchers found that all subjects exposed to blue light had a delay in melatonin release, and those exposed to light at 460 nm had at least a 65% reduction in melatonin.

Blue light can suppress the production of melatonin, a hormone that regulates sleep, disrupting circadian rhythm, which can lead to difficulty falling asleep and disrupted sleep patterns.

Dr. Chester Wu

In another study, Harvard researchers investigated how 6.5 hours of blue light exposure would impact the participants’ melatonin and circadian rhythm compared to green light of comparable brightness. They concluded that the blue light suppressed melatonin for about twice as long as the green light and shifted circadian rhythms by twice as much (3 hours vs. 1.5 hours).

A group of the population that spends an alarmingly large amount of time on electronics is adolescents. Hence, a cross-sectional community-based study looked at how such devices would impact the sleep quality of 9,846 adolescents aged 16–19. The findings revealed that using electronics led to an “increased risk of short sleep duration, long sleep onset latency, and increased sleep deficiency.”

The number of studies that investigate the impact of blue light exposure on sleep continues to grow for a very good reason. However, there is no definite conclusion on whether it makes a difference in sleep parameters.

A systematic review published in Frontiers in Physiology found conflicting results from previous studies on whether blue light exposure would negatively impact sleep quality, duration, and efficiency. According to the review, some studies reported blue light decreased sleep duration and efficiency and led to increased sleep latency, but others investigating the same objectives found no significant change.

The authors noted that “in general, the specific effects of blue light exposure seem still to be a murky field, and more investigations are needed before final firm and evidence-based conclusions can be drawn.”

How blue-light-blocking glasses work

Blue-light-blocking glasses work by filtering out the blue light emitted by electronic devices. Blue-light-blocking glasses help to reduce the amount of blue light that reaches the eyes, thereby may reduce its impact on sleep. Dr. Wu and Dr. Ford recommend wearing them for at least an hour and a half to two hours before bedtime. This allows the body to produce melatonin naturally in response to reduced exposure to blue light.

It can be impractical to peg the timing of use to the sunset because the time the sun sets changes daily, and your sleep schedule should ideally be more consistently timed. Other lighting considerations should be taken into account before bed as well. Dim overhead lights also within the hours before bed,

Dr. Chester Wu

As the pineal gland begins to secrete melatonin, it allows the body to start cooling core body temperature, which, as Dr. Ford explained, helps “reduce alertness, making the transition to sleep easier if one has sufficient sleep debt built up across the day.”

Do blue-light blockers really work?

Dr. Ford explained that studies have found blue-light glasses to improve time to fall asleep and, in some cases, total sleep time for people with insomnia and circadian rhythm sleep disorders such as shift-work disorder, jet lag, and delayed sleep-phase disorder. However, it may be less significant for the general public.

“Studies of those without sleep disorders are equivocal, and generally speaking, studies in the field are of low quality. So these glasses are unlikely to be necessary for normal sleepers,” Dr. Ford said.

Furthermore, the tint of the glasses also matters. When in search of blue-light blockers, one may come across lenses of various colors: clear, yellow, amber, and even red. Experts say the more tinted they are, the more they filter out blue light.

Orange- or amber-tinted glasses are more effective at blocking blue light than blue- or yellow-tinted glasses, clear glasses do not block blue light at all. It is important to choose glasses that specifically state that they block blue light and have been tested to do so.

Dr. Chester Wu

Dr. Ford also highlighted the importance of looking for manufacturers that have studies to back the efficacy of their glasses.

A randomized controlled trial showed wearing amber versus clear lenses for a couple of hours preceding bedtime for one week improved sleep in individuals with insomnia symptoms.

Another study comparing the use of amber blue-blocking lenses versus yellow-tinted safety glasses, which only block ultraviolet light, for three hours prior to sleep found that the group weaning the amber lenses experienced significant improvement in sleep quality relative to the control group. Plus, they have also seen improvements in mood.

Are blue-light-blocking glasses for you?

The conflicting evidence may be due to the fact that each human has their own bio individual response to blue light and how it affects their sleep, and hence, there’s no general conclusion to draw.

Dr. Ford pointed out that a range of studies reports that blue light may reduce melatonin production and delay sleep onset, and possibly disrupt sleep. “However, the overall effect in real life appears to be small,” he said. “For example, reading an e-book for four hours before bedtime for five nights suppressed melatonin by an average of 55%. But, the overall result was an increase of 10 minutes to fall asleep, a reduction in REM sleep by 10 minutes, and no other changes to sleep. That's not a big deal.”

Additionally, Dr. Wu noted it might not only be light on its own that keeps you up at night. “When it comes to screens at night, wearing blue light-blocking glasses should not be the only consideration,” he said. “Newer research shows screen time can also challenge sleep by cutting into sleep time as well as over-stimulate us through the content we consume, making it harder to fall asleep.”

If you have a sleep disorder, such as insomnia, shift-work disorder, or delayed sleep-phase disorder, science shows that you may benefit from wearing blue-light blockers up to a couple of hours before bedtime, especially if you spend a lot of time looking at digital screens in the evening. This may help signal your body to release melatonin, so you can best ease into sleep when your head hits the pillow.

If you don’t have a sleep disorder but are traveling across time zones, wearing blue-light blockers may help your circadian rhythm adjust to the new time more easily.

If neither applies to you at the moment, the verdict is that blue-light-blocking glasses may or may not benefit your sleep. However, wearing them certainly will not hurt. Thus, if you are curious, give it a shot. Just remember to choose a brand that proves its glasses' efficacy and is ideally tinted yellow, amber, or orange for best results.