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How To Perform the 4-7-8 Breathing Exercise | Andrew Weil, M.D.

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Free app with timer for self-guided medication, relaxing music, & guided meditations.

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What's the Hype? Blue Light-Blocking Glasses

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What's the Hype? Blue Light-Blocking Glasses

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Recently, my brother mentioned he was sleeping better since he got new prescription glasses with a blue-light filter. He wears his glasses mostly for reading screens (both computer and smartphone) during the day while at work. So I was intrigued, but a little skeptical: could daytime use of blue light-filtering glasses make a difference in how well he slept? How, when, and why blue light affects us seemed like good questions to pose to an expert before deciding whether those glasses could help me, too.

What is blue light?

Visible light includes a short segment of wavelengths tucked into the electromagnetic radiation spectrum. Together, the wavelengths of visible light captured by our eyes are translated into white light by our brains.

You may remember looking through a prism to bend the wavelengths that make up white light into a rainbow of colors. At one end of this rainbow, blue light shades toward violet. Sunlight has a lot of light at all visible wavelengths.

Measured in nanometers (nm), visible light wavelengths range from 400 to 700 nm. Blue-light wavelengths lie between about 450 and 495 nm. And different slices of blue-light wavelengths have different effects on our bodies, including on sleep and alertness.

How does light affect our bodies?

In addition to helping us see, light also has nonvisual effects on the body, says Dr. Steven Lockley, a neuroscientist at the Division of Sleep and Circadian Disorders at Harvard-affiliated Brigham and Women's Hospital.

The 24-hour circadian clock in the brain regulates sleep and wake cycles, hormonal activity, eating and digesting, and other important processes within the body. "Special photoreceptors in the eye detect light to control our circadian rhythms," he says. These cells contain a nonvisual photopigment called melanopsin, which is most sensitive to 480 nm light at the blue-green end of the visible light spectrum. Other visual photoreceptors called cones allow us to see even shorter wavelengths of blue-violet light at around 450 nm.

How can blue light affect sleep?

During the day blue-enriched light is desirable, because it helps synchronize our circadian clocks to a 24-hour day. So, exposure to a regular light-and-dark cycle is vital to achieve and maintain good sleep.

Stimulation from certain wavelengths of blue light helps us stay alert, whether this comes from a natural source like the sun in daytime hours, or from electronic devices that emit blue light. While the stimulation is helpful during the day, at night it can interfere with sleep. Blue-light exposure in the evening - for example, binging a TV series on your laptop right before bed - will stimulate the melanopsin-containing cells and alert the brain, making it think it is daytime. That can make it harder to fall asleep and may affect the quality of your sleep.

Blue-light filtering: Can it help a tired body and tired eyes?

Although a recent systematic review suggested that blue light-blocking glasses may help people with insomnia, Dr. Lockley says there's not enough detail about the studies to draw that conclusion. Most commercially available blue light-filtering glasses, and special coatings added to prescription lenses, aren't standardized. So you have no way of knowing which wavelengths are being blocked, and whether this affects only visual function, or important nonvisual functions such as alertness and the circadian clock. Also, the timing, duration, and nature of the nighttime light exposure in the summary of these studies was not clear.

If you want to block stimulating blue light that could interfere with sleep, avoid screen use as much as possible after dusk - especially within two to three hours of bedtime. You can also try using computer software that reduces the amount of blue light emitted. Examples include Night Shift (available on Apple devices) or f.lux, a free download available for all computers and related devices. You should also try to address other issues that affect your sleep.

To help reduce eye strain, a common concern for people who use screens often, the American Academy of Ophthalmology advises taking regular breaks using the 20-20-20 rule. Every 20 minutes, look away from your screen at an object about 20 feet away for about 20 seconds.

You should also get as much daylight exposure as possible in between screen use to provide a strong circadian and alerting stimulus, particularly if you spend most of your time indoors.

As for my brother, he doesn't watch much television and tends to prefer reading print books in the evenings. He agreed that he might be experiencing a placebo effect from the blue-light filter on his new glasses - or simply that he is sleeping better now that he has the correct prescription, and therefore less eye strain.

About the Author

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Can blue light-blocking glasses improve your sleep? - Harvard Health

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Exposure to blue light during the daytime is desirable: it helps synchronize the body's circadian clock and helps people stay alert. But stimulation from certain wavelengths of blue light in the hours leading up to bedtime can interfere with sleep. Glasses that block stimulating blue light, whether prescription or not, ...

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Pink noise contains all the sound frequencies that humans can hear. Unlike white noise-which represents all the frequencies equally-the higher frequencies in pink noise are less intense.

For many people, pink noise can block out annoying background sounds without sounding harsh or shrill. Some people use pink noise to help them sleep.

This article will go over what pink noise is. You'll learn how pink noise is different from white noise and brown noise, why you might want to try using pink noise, and whether listening to pink noise can be harmful.

How Pink Noise Works

Pink noise is a noise "color" like white noise. The colors are used to describe the frequencies that are in the noise.

Colors of Light and Sound

Using colors to describe sounds comes from how we talk about the colors on the spectrum of light that we can see.

For example, white light includes all colors on the spectrum. Similarly, white noise has all frequencies of sound in it that humans can hear.

Some common examples of white noise are a running vacuum and television static. These sounds can be used to block out unwanted noises when people are trying to focus or sleep.

The problem with white noise is that all the frequencies come through at the same intensity. Human ears don't really like high-pitched sounds, so white noise be annoying or even unpleasant for some people.

Pink noise tries to fix this problem. Pink noise still has all audible sounds, but the lower frequencies are amplified and the higher frequencies are diminished.

The key to pink noise is that the higher frequencies are less intense. Since they are "gentler," your ears are less likely to get overwhelmed by them. The calming lower frequencies can make pink noise sound more soothing.

Examples of Pink Noise

Many natural sounds are examples of pink noise-for example, waves crashing on a beach, leaves rustling in the trees, and rain falling.

That said, not all natural sounds are pink noise. Sounds that emphasize low frequencies even more than pink noise are called brown noise. For example, thunder or the sound of a far-off waterfall are examples of brown noise.

Can Pink Noise Help With Sleep?

There's a lot of evidence that using sound to cover up background noises can help people sleep better, but most of that research was been done on white noise:

One study found that white noise helped hospital patients fall asleep 40% faster.

White noise may help infants sleep better and may even help kids concentrate in school.

Research has suggested that pink noise can help with sleep, too. Pink noise might even boost memory since our memories are stored when we're in deep sleep.

Here are a few examples of what studies have found about pink noise:

A 2017 study looked at the effect of pink noise on sleep in a small group of 13 older adults. The study found that listening to pink noise while sleeping increased slow wave activity in the brain, which is associated with deep sleep.

A similar study in 2016 found that pink noise improved sleep and memory for younger adults who were taking a daytime nap.

Two studies, in 2012 and 2013, also found that exposure to pink noise could lead to deeper sleep, longer sleep, and improved memory. The findings were true for nighttime sleep and daytime naps.

Should I Listen to Pink Noise or Another Color?

Pink noise is just one of several noise colors. While people often refer to any noise that's meant to mask background sounds as white noise, not all of those sounds are actually white noise. There are actually two more colors of noise: brown and blue.

Here are some of the benefits of each noise color:

White noise: Represents all audible sound frequencies equally. It's good at masking background noises, but some people find it annoying to listen to because their ears hear the high-frequency noises the most.

Pink noise: Includes the full range of audible sounds, but the lower frequencies are amplified, and the higher frequencies are diminished. It sounds more soothing to many people who might find white noise annoying.

Brown noise: Brown noise contains all sound frequencies, but the low, bass tones are strongest.

Blue noise: Blue noise is the opposite of brown noise. It contains all the audible frequencies, but the higher-pitched frequencies are amplified. To most people, blue noise sounds harsh, so it's not a common option for sleep support. However, some people still find it helpful.

Can Pink Noise Be Harmful?

It's not clear whether listening to pink noise (or any other color noise) can be harmful. Often, the worst thing that happens is that someone tries listening to pink sound and just finds that it "doesn't do anything for them."

However, we're still learning about how white, brown, and pink noise might affect us, including whether it has benefits for focus and sleep or whether listening to it might have health risks.

While some research has suggested that people may sleep better with white noise, experts say that it may not benefit everyone. Some studies have shown that certain colors of noise might actually make sleep worse.

Whatever color you're listening to, any noise can be harmful to you if it's too loud. If you're listening to any sounds (especially with headphones) make sure that you're listening at a safe, comfortable volume and that you give your ears a break (for example, setting your noise app timing to shut off after you've fallen asleep).

How to Find a Pink Noise Machine

A pink noise machine is not as easy to come by as a white noise machine. Some apps have clearly labeled sounds for pink noise, white noise, and even brown noise. Even if they don't, you might be able to find pink sounds if you know what to look for.

Many noise machine apps actually do have pink noise options even if they don't specifically call it pink noise-for example, waves crashing on the beach or light rainfall.

Pink noise is one of the many "colors" of noise that some people use to help drown out background noise, improve their focus, or even help them sleep better.

There's more research on white noise than other noise colors, but some studies have shown that pink noise might help with sleep and concentration.

You won't know which noise color works best for you until you try them out. One of the easiest ways to see if pink noise works for you is to use a pink noise machine or app. If you're not sure what your pink noise options are, look for sounds like waves crashing or gentle rainfall.

Frequently Asked Questions

Is pink noise good for anxiety?

Some people find that pink noise is best for their anxiety. Pink noise might be best for anxiety because it's a lower frequency than white noise.

Does pink noise help ADHD?

The best color noise if you have ADHD isn't clear; it may come down to personal preference. In some studies, white noise was found to be most helpful to people with ADHD who were trying to focus. Other research has found that brown noise tends to be more beneficial for ADHD.

What if pink noise doesn't help me sleep?

If you've been trying to get better sleep with pink noise and it's not working, remember that practicing good sleep hygiene is also important.

Going to bed and waking up at roughly the same time each day, keeping your bedroom dark, and minimizing your use of electronics in the bedroom are steps you can take to get better sleep.

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Pink noise is like white noise, but less harsh on the ears because the lower tones are amplified. Pink noise may help with sleep and memory.