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Hear the Rainbow: How the Color of Noise Affects the Brain

Many of us need a little help winding down and blocking out our environment at night, and ambient noise is a great way to do it. Since they’re constant in volume and completely unpatterned, they block out other noises while encouraging your brain to chill out and lay down for the night.

But how do these noises work? And is there really a difference between the white, blue, pink, and brown kinds? To understand white and other color noises as they’re used to help sleep, we need to do a quick science lesson first:

Super-Short Sleep Psych: Brain Waves During Sleep

Who knew you were gonna do a bite-size psychology class today, right?

In general, brain waves slow as activity slows, meaning brain waves when you’re awake are faster than when you’re relaxed, than when you’re in light sleep, than when you’re in deep sleep. There are brain waves that characterize drowsiness, followed by five stages of sleep, each with its own set of wave frequencies:

  • Relaxed/Drowsy: Alpha waves (8 - 12.99 Hz)

  • Stage 1: Theta waves (4 - 7.99 Hz)

  • Stage 2: Progressive theta waves (4 - 7.99 Hz)

  • Stage 3: Delta waves (1 - 3.99 Hz)

  • Stage 4 (REM): Theta (4 - 7.99 Hz), beta (16 - 31.99 Hz) and gamma (32+ Hz) waves

As you can see, REM sleep doesn’t follow the slow-down pattern. That’s because it’s kind of a light and active sleep stage. REM sleep is all-important for solidifying memories, encouraging brain development, processing emotions, promoting cognitive health – the list goes on. And the brain waves observed during REM sleep reflect that activity – they look almost the same as awake wave patterns.

Throughout the night, you cycle through these non-REM stages, into REM, and then over again, several times each night. Aside from REM, the deep sleep stages are vital for allowing the brain and body to biologically rest and restore themselves each night. To get the quality sleep you need, moving through these stages without constantly waking/interrupting them is key.

Class over. See? Super-short.

So then, let’s look at the different colors of noise and how they encourage our brain to concentrate on resting and restoring itself all night instead of waking up every time that branch hits the corner of the bedroom window:

White Noise

Just like white light is a blend of all colors of light visible to the human eye, white noise is all frequencies audible to the human ear at once at equal energy. White noise helps block out distractions, allowing you to reach that alpha wave vibe and stay there. Some studies have shown that white noise helps cognition in kids with ADHD. It’s also often recommended for people with insomnia.

However, some studies have also shown that white noise can have long-term negative effects on the brain by unteaching it how to block out distractions on its own. It’s also not good for tinnitus, and may actually increase brain aging.

Black Noise

This one’s a little tricky, because black noise is silence. It’s mostly zero power levels on all frequencies with an occasional, non-patterned rise and fall. Turns out silence is, in fact, a sound. This noise causes the brain to feel an absence of noise (but not the kind that causes hallucinations), allowing you to relax and lay back into those sleepier frequencies.

Blue Noise

Blue noise is often described as the hiss of water spraying from a hose. Blue noise blocks and smooths everything out, clearing a path to a meditative, relaxed state. However, it’s biased to higher frequencies. This might be great for people who aren’t sensitive to higher frequencies, but it’s not good for people with tinnitus or troubled sleepers.

Brown Noise

Also called red noise, is a much deeper variation on white noise, as it has higher energies at the lower frequencies. The human ear is thought to prefer lower frequencies. There isn’t a tonne of clinical research to say brown noise works, but it’s an extremely popular choice for inducing sleep. Thought still not ideal, darker noises also tend to be better choices for people with tinnitus.

Grey Noise

Grey noise is different than the other full-spectrum noises, as instead of equal energy across all bands, it’s equal volume across all bands. Each individual’s brain decides which frequencies it prefers, focusing in on some more than others. Which means grey noise is different for everyone and at every volume.

Good news – this color noise is actually recommended for people with tinnitus!

Green Noise

Green noise is a low-frequency sleep sound, at about 500 Hz (Remember: we can hear up to 20000 Hz). It’s often called “the sound of nature,” as the frequencies of moving water – think streams and waterfalls – are included in this band. Green noise is great at sound-masking, and since it’s distinctly-lower than the other color sounds (besides black, of course), it may be the most effective at helping you get to sleep and stay that way.

Pink Noise

Perhaps the most popular choices for ambient sleep noises, along with white and brown/red, is pink noise. Basically the middle point between the two, pink noise is also the spectrum of audible waves, but it’s biased toward the lower frequencies.

Pretty cool, right? Maybe the key to getting a better night’s sleep is to make the night noisier. And to make sure you’re doing it on a super-comfy custom mattress, of course.


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