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Blue Light and Insomnia: Is It a Myth? (Do Glasses Work?)

by Dale Cudmore | Updated: Jul 21, 2021

Plenty of people seem to have no problem falling asleep while watching tv or using a computer, so is blue light really as bad as people say it is?

Blue light is healthy during the day, but research overwhelmingly shows that it has a negative effect on sleep quality.

The biggest effect that it has is delaying melatonin production, which lengthens the time it takes to get to sleep. There are certainly people who can still get to sleep relatively quickly, but considering how many people have sleep issues, blue light plays a major role.

I’m going to walk you through the most important research on this topic so you can learn just how impactful blue light exposure at night is, and what you can do about it.

How Does Blue Light Affect Sleep?

Blue light is simply a portion of the visible light spectrum.

Some light sources contain more light of that frequency range than others, but just about all light sources (e.g. bulbs, screens) emit at least some blue light.

While the effects of blue light on sleep are pretty clear, it also affects us during the day.

That’s because blue light affects the circadian rhythm, which is the summation of complex processes that control how alert or tired you are.

Research has shown that blue-wavelength light increases blood pressure and overall arousal (stress and anxiety) (1).

These effects are pretty obviously not good while trying to sleep, but are useful during the day. Those effects of blue light improve a variety of performance related attributes including (2):

  • Memory
  • Alertness
  • Reaction time
  • Cognitive performance

SummaryAll of this is why getting blue light from sunlight during the day is good. But during night, blue light suppresses melatonin production, which delays the sleep portion of your circadian rhythm from kicking in properly.

Can Blue Light Blocking Glasses Improve Insomnia?

The majority of studies on blue light have looked at how blue light blocking glasses may be able to improve sleep. Considering most people get way too much blue light in general, this approach makes sense.

Back in 2008 when blue light first really rose to mainstream attention, a 3 week study on 20 adults had subjects wear either blue light blocking or basic UV glasses (control group) for 3 hours before sleep (3). They found:

At the end of the study, the amber lens group experienced significant improvement in sleep quality relative to the control group. Mood also improved significantly relative to controls.

That’s a small study, but it was one of the first to justify further investigation into this topic, and several researchers have since replicated and built on this work.

A 2018 study had patients with insomnia wear blue light blocking amber lenses for 2 hours before bedtime for 7 nights in a row (4).

The most important findings included:

Reported wake-time was significantly delayed, and mean subjective total sleep time (TST), overall quality, and soundness of sleep were significantly higher in amber vs. clear lenses condition over the 7-d intervention period. 

Total sleep time increased by about 15% in the blue light blocking group.

At this point, many studies have reliably confirmed this effect.

One study looked at whether adding blue light blocking glasses on top of cognitive behavioral therapy for insomnia (CBT-i) would be more effective than CBT-i by itself (5).

It was a small sample size, but there were statistically significant improvements in total sleep time and anxiety scores in the group with both CBT-i and glasses versus just the CBT-i.

SummaryWhile there are still areas of research to explore, wearing blue light blocking glasses in the hours leading up to sleep is a cheap and convenient way to improve overall sleep quality.

Blue Light Glasses and ADHD Insomnia

There are a few other specific scenarios that have been researched that I wanted to touch upon.

The first is one study that looked at the effect of this type of glasses in people who suffer from ADHD insomnia (6).

The results were really impressive:

Global PSQI scores fell from 11.15 to 4.54, dropping below the cut-off score of 5 for clinical insomnia

If you’d like to learn more about PSQI, see our free online PSQI calculator.

Considering the effect of blue light on the sympathetic nervous system, it’s not surprising that blocking blue light could have a calming effect in those with ADHD.

Blue Light Glasses and Delayed Sleep Phase Disorder

One other condition that research suggests that blue light glasses can help with is delayed sleep phase disorder. This is a disorder where people seem to “naturally” fall asleep later than usual and have a hard time waking up.

A study found that blue light blocking glasses were able to advance sleep onset in patients with this disorder by 132 minutes back to a healthy time (7).

This suggests that many people with delayed sleep phase disorder simply get too much blue light exposure.

Is Blocking All Blue Light Good?

It’s easy to see the research above and decide to wear blue light blocking glasses from say 5pm and expect to sleep like a baby.

But you need to be careful about blocking blue light, because getting enough during the day especially is important.

As we age, the natural lens of the eye filters out an increasing portion of blue light. Research is now suggesting that this could be one of the major causes of sleep issues in old age (although there are other known factors).

One study found a clear association between the degree of lens yellowing (which is responsible for filtering out blue light) and sleep disturbances (8).

SummaryNot getting enough blue light exposure during the day can lead to increased sleep disturbances at night, whether it’s from glasses or naturally from aging.

Alternatives to Blue Light Blocking Glasses

Blue light blocking glasses are by far the most affordable and simple way to reduce blue light exposure.

Many modern screens also come with “easy on the eye” settings for viewing at night. Software like Flux can also reduce blue light emitted from laptops at night.

Finally, remember that just about all light sources emit some blue light, so dim and turn off as many lights as you can at night in your house.

Similarly, block out as much external lighting (e.g. street lights) using blackout curtains if possible.

Summary: How Does Blue Light Affect Sleep?

To recap, we’ve seen that blue light affects the circadian rhythm by promoting alertness and delaying the formation of melatonin (the “sleepiness” hormone).

The effect it has on sleep is most certainly not a myth at this point, a lot of research clearly shows the impact blue light can have, so if you can avoid watching tv before bed you should.

In people with otherwise good sleep hygiene, it doesn’t usually have a huge effect by itself, but in others, it can lead to insomnia.

Consider that blue light makes it take longer to get to sleep, and also makes you more anxious. In people who are already fairly anxious, this can lead to sleep anxiety (worrying about getting to sleep), which leads to even worse insomnia.

This cycle can repeat itself until someone develops chronic insomnia, and even fixing the blue light exposure at that point probably won’t be enough to get back to good sleep quality. At that point, a comprehensive treatment plan for insomnia from a doctor is usually required.

References

  1. A behavioral intervention for insomnia improves blood pressure
  2. Blue Light: A Blessing or a Curse?
  3. Amber Lenses to Block Blue Light and Improve Sleep
  4. Blocking nocturnal blue light for insomnia: A randomized controlled trial
  5. Evening blue light filtration as a part of cognitive behavioral therapy for insomnia
  6. Treatment of attention deficit hyperactivity disorder insomnia with blue wavelength light-blocking glasses
  7. Wearing blue light-blocking glasses in the evening advances circadian rhythms in the patients with delayed sleep phase disorder
  8. Sleep Disturbances Are Related to Decreased Transmission of Blue Light to the Retina Caused by Lens Yellowing

Medical Disclaimer: The information on SnoozeUniversity.com is not intended to be a substitute for physician or other qualified care. We simply aim to inform people struggling with sleep issues about the nature of their condition and/or prescribed treatment.


About the authorDale is the founder of Snooze University and a sleep researcher. I overcame my sleep issues and now I'd like to help you do the same by summarizing the latest sleep studies for you.